diff --git a/gio/gactiongroup.c b/gio/gactiongroup.c
index 73d1ca353..30e5e137d 100644
--- a/gio/gactiongroup.c
+++ b/gio/gactiongroup.c
@@ -699,10 +699,10 @@ g_action_group_action_state_changed (GActionGroup *action_group,
  * @action_group: a #GActionGroup
  * @action_name: the name of an action in the group
  * @enabled: (out): if the action is presently enabled
- * @parameter_type: (out): the parameter type, or %NULL if none needed
- * @state_type: (out): the state type, or %NULL if stateless
- * @state_hint: (out): the state hint, or %NULL if none
- * @state: (out): the current state, or %NULL if stateless
+ * @parameter_type: (out) (allow-none): the parameter type, or %NULL if none needed
+ * @state_type: (out) (allow-none): the state type, or %NULL if stateless
+ * @state_hint: (out) (allow-none): the state hint, or %NULL if none
+ * @state: (out) (allow-none): the current state, or %NULL if stateless
  *
  * Queries all aspects of the named action within an @action_group.
  *
diff --git a/gio/gapplication.c b/gio/gapplication.c
index fe01d2a43..410f854d4 100644
--- a/gio/gapplication.c
+++ b/gio/gapplication.c
@@ -1135,7 +1135,7 @@ g_application_get_is_remote (GApplication *application)
 /**
  * g_application_register:
  * @application: a #GApplication
- * @cancellable: a #GCancellable, or %NULL
+ * @cancellable: (allow-none): a #GCancellable, or %NULL
  * @error: a pointer to a NULL #GError, or %NULL
  *
  * Attempts registration of the application.
@@ -1682,7 +1682,7 @@ g_application_get_default (void)
 
 /**
  * g_application_set_default:
- * @application: the application to set as default, or %NULL
+ * @application: (allow-none): the application to set as default, or %NULL
  *
  * Sets or unsets the default application for the process, as returned
  * by g_application_get_default().
diff --git a/gio/gapplicationcommandline.c b/gio/gapplicationcommandline.c
index 773e5df99..c51f45d98 100644
--- a/gio/gapplicationcommandline.c
+++ b/gio/gapplicationcommandline.c
@@ -326,7 +326,7 @@ g_application_command_line_class_init (GApplicationCommandLineClass *class)
 /**
  * g_application_command_line_get_arguments:
  * @cmdline: a #GApplicationCommandLine
- * @argc: (out): the length of the arguments array, or %NULL
+ * @argc: (out) (allow-none): the length of the arguments array, or %NULL
  *
  * Gets the list of arguments that was passed on the command line.
  *
diff --git a/gio/gasyncinitable.c b/gio/gasyncinitable.c
index e2264e0f6..4d0c0978f 100644
--- a/gio/gasyncinitable.c
+++ b/gio/gasyncinitable.c
@@ -318,7 +318,7 @@ g_async_initable_real_init_finish (GAsyncInitable  *initable,
  * @callback: a #GAsyncReadyCallback to call when the initialization is
  *     finished
  * @user_data: the data to pass to callback function
- * @first_property_name: the name of the first property, or %NULL if no
+ * @first_property_name: (allow-none): the name of the first property, or %NULL if no
  *     properties
  * @...:  the value of the first property, followed by other property
  *    value pairs, and ended by %NULL.
diff --git a/gio/gcancellable.c b/gio/gcancellable.c
index 06d2fa7d7..8fb119522 100644
--- a/gio/gcancellable.c
+++ b/gio/gcancellable.c
@@ -362,7 +362,7 @@ g_cancellable_get_fd (GCancellable *cancellable)
 
 /**
  * g_cancellable_make_pollfd:
- * @cancellable: a #GCancellable or %NULL
+ * @cancellable: (allow-none): a #GCancellable or %NULL
  * @pollfd: a pointer to a #GPollFD
  * 
  * Creates a #GPollFD corresponding to @cancellable; this can be passed
@@ -523,7 +523,7 @@ g_cancellable_cancel (GCancellable *cancellable)
  * @cancellable: A #GCancellable.
  * @callback: The #GCallback to connect.
  * @data: Data to pass to @callback.
- * @data_destroy_func: Free function for @data or %NULL.
+ * @data_destroy_func: (allow-none): Free function for @data or %NULL.
  *
  * Convenience function to connect to the #GCancellable::cancelled
  * signal. Also handles the race condition that may happen
@@ -584,7 +584,7 @@ g_cancellable_connect (GCancellable   *cancellable,
 
 /**
  * g_cancellable_disconnect:
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @handler_id: Handler id of the handler to be disconnected, or %0.
  *
  * Disconnects a handler from a cancellable instance similar to
@@ -709,7 +709,7 @@ static GSourceFuncs cancellable_source_funcs =
 
 /**
  * g_cancellable_source_new: (skip)
- * @cancellable: a #GCancellable, or %NULL
+ * @cancellable: (allow-none): a #GCancellable, or %NULL
  *
  * Creates a source that triggers if @cancellable is cancelled and
  * calls its callback of type #GCancellableSourceFunc. This is
diff --git a/gio/gdbusaddress.c b/gio/gdbusaddress.c
index 77aff1279..b9509ef21 100644
--- a/gio/gdbusaddress.c
+++ b/gio/gdbusaddress.c
@@ -824,7 +824,7 @@ get_stream_thread_func (GSimpleAsyncResult *res,
 /**
  * g_dbus_address_get_stream:
  * @address: A valid D-Bus address.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @callback: A #GAsyncReadyCallback to call when the request is satisfied.
  * @user_data: Data to pass to @callback.
  *
@@ -913,7 +913,7 @@ g_dbus_address_get_stream_finish (GAsyncResult        *res,
  * g_dbus_address_get_stream_sync:
  * @address: A valid D-Bus address.
  * @out_guid: %NULL or return location to store the GUID extracted from @address, if any.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @error: Return location for error or %NULL.
  *
  * Synchronously connects to an endpoint specified by @address and
@@ -1163,7 +1163,7 @@ get_session_address_platform_specific (GError **error)
 /**
  * g_dbus_address_get_for_bus_sync:
  * @bus_type: A #GBusType.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @error: Return location for error or %NULL.
  *
  * Synchronously looks up the D-Bus address for the well-known message
diff --git a/gio/gdbusauthobserver.c b/gio/gdbusauthobserver.c
index b3a13532d..a55e13df6 100644
--- a/gio/gdbusauthobserver.c
+++ b/gio/gdbusauthobserver.c
@@ -143,7 +143,7 @@ g_dbus_auth_observer_class_init (GDBusAuthObserverClass *klass)
    * GDBusAuthObserver::authorize-authenticated-peer:
    * @observer: The #GDBusAuthObserver emitting the signal.
    * @stream: A #GIOStream for the #GDBusConnection.
-   * @credentials: Credentials received from the peer or %NULL.
+   * @credentials: (allow-none): Credentials received from the peer or %NULL.
    *
    * Emitted to check if a peer that is successfully authenticated
    * is authorized.
@@ -192,7 +192,7 @@ g_dbus_auth_observer_new (void)
  * g_dbus_auth_observer_authorize_authenticated_peer:
  * @observer: A #GDBusAuthObserver.
  * @stream: A #GIOStream for the #GDBusConnection.
- * @credentials: Credentials received from the peer or %NULL.
+ * @credentials: (allow-none): Credentials received from the peer or %NULL.
  *
  * Emits the #GDBusAuthObserver::authorize-authenticated-peer signal on @observer.
  *
diff --git a/gio/gdbusconnection.c b/gio/gdbusconnection.c
index 44bda5d5e..2a1f09003 100644
--- a/gio/gdbusconnection.c
+++ b/gio/gdbusconnection.c
@@ -249,8 +249,8 @@ call_destroy_notify_data_free (CallDestroyNotifyData *data)
 
 /*
  * call_destroy_notify: <internal>
- * @context: A #GMainContext or %NULL.
- * @callback: A #GDestroyNotify or %NULL.
+ * @context: (allow-none): A #GMainContext or %NULL.
+ * @callback: (allow-none): A #GDestroyNotify or %NULL.
  * @user_data: Data to pass to @callback.
  *
  * Schedules @callback to run in @context.
@@ -1209,7 +1209,7 @@ flush_in_thread_func (GSimpleAsyncResult *res,
 /**
  * g_dbus_connection_flush:
  * @connection: A #GDBusConnection.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @callback: (allow-none): A #GAsyncReadyCallback to call when the request is
  *            satisfied or %NULL if you don't care about the result.
  * @user_data: The data to pass to @callback.
@@ -1294,7 +1294,7 @@ g_dbus_connection_flush_finish (GDBusConnection  *connection,
 /**
  * g_dbus_connection_flush_sync:
  * @connection: A #GDBusConnection.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @error: Return location for error or %NULL.
  *
  * Synchronously flushes @connection. The calling thread is blocked
@@ -1408,7 +1408,7 @@ schedule_closed_unlocked (GDBusConnection *connection,
 /**
  * g_dbus_connection_close:
  * @connection: A #GDBusConnection.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @callback: (allow-none): A #GAsyncReadyCallback to call when the request is
  *            satisfied or %NULL if you don't care about the result.
  * @user_data: The data to pass to @callback.
@@ -1522,7 +1522,7 @@ sync_close_cb (GObject *source_object,
 /**
  * g_dbus_connection_close_sync:
  * @connection: A #GDBusConnection.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @error: Return location for error or %NULL.
  *
  * Synchronously closees @connection. The calling thread is blocked
@@ -1985,7 +1985,7 @@ g_dbus_connection_send_message_with_reply_unlocked (GDBusConnection     *connect
  *                timeout or %G_MAXINT for no timeout.
  * @out_serial: (out) (allow-none): Return location for serial number assigned
  *              to @message when sending it or %NULL.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @callback: (allow-none): A #GAsyncReadyCallback to call when the request is
  *            satisfied or %NULL if you don't care about the result.
  * @user_data: The data to pass to @callback.
@@ -2120,7 +2120,7 @@ send_message_with_reply_sync_cb (GDBusConnection *connection,
  *                timeout or %G_MAXINT for no timeout.
  * @out_serial: (out) (allow-none): Return location for serial number assigned
  *              to @message when sending it or %NULL.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @error: Return location for error or %NULL.
  *
  * Synchronously sends @message to the peer represented by @connection
@@ -2665,7 +2665,7 @@ async_initable_iface_init (GAsyncInitableIface *async_initable_iface)
  * @guid: (allow-none): The GUID to use if a authenticating as a server or %NULL.
  * @flags: Flags describing how to make the connection.
  * @observer: (allow-none): A #GDBusAuthObserver or %NULL.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @callback: A #GAsyncReadyCallback to call when the request is satisfied.
  * @user_data: The data to pass to @callback.
  *
@@ -2753,7 +2753,7 @@ g_dbus_connection_new_finish (GAsyncResult  *res,
  * @guid: (allow-none): The GUID to use if a authenticating as a server or %NULL.
  * @flags: Flags describing how to make the connection.
  * @observer: (allow-none): A #GDBusAuthObserver or %NULL.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @error: Return location for error or %NULL.
  *
  * Synchronously sets up a D-Bus connection for exchanging D-Bus messages
@@ -2803,7 +2803,7 @@ g_dbus_connection_new_sync (GIOStream             *stream,
  * @address: A D-Bus address.
  * @flags: Flags describing how to make the connection.
  * @observer: (allow-none): A #GDBusAuthObserver or %NULL.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @callback: A #GAsyncReadyCallback to call when the request is satisfied.
  * @user_data: The data to pass to @callback.
  *
@@ -2888,7 +2888,7 @@ g_dbus_connection_new_for_address_finish (GAsyncResult  *res,
  * @address: A D-Bus address.
  * @flags: Flags describing how to make the connection.
  * @observer: (allow-none): A #GDBusAuthObserver or %NULL.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @error: Return location for error or %NULL.
  *
  * Synchronously connects and sets up a D-Bus client connection for
@@ -5576,7 +5576,7 @@ g_dbus_connection_call_sync_internal (GDBusConnection         *connection,
  * @flags: Flags from the #GDBusCallFlags enumeration.
  * @timeout_msec: The timeout in milliseconds, -1 to use the default
  *                timeout or %G_MAXINT for no timeout.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @callback: (allow-none): A #GAsyncReadyCallback to call when the request is
  *            satisfied or %NULL if you don't care about the result of the
  *            method invocation.
@@ -5678,7 +5678,7 @@ g_dbus_connection_call_finish (GDBusConnection  *connection,
  * @flags: Flags from the #GDBusCallFlags enumeration.
  * @timeout_msec: The timeout in milliseconds, -1 to use the default
  *                timeout or %G_MAXINT for no timeout.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @error: Return location for error or %NULL.
  *
  * Synchronously invokes the @method_name method on the
@@ -5758,7 +5758,7 @@ g_dbus_connection_call_sync (GDBusConnection         *connection,
  * @timeout_msec: The timeout in milliseconds, -1 to use the default
  *                timeout or %G_MAXINT for no timeout.
  * @fd_list: (allow-none): A #GUnixFDList or %NULL.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @callback: (allow-none): A #GAsyncReadyCallback to call when the request is
  *            satisfied or %NULL if you don't * care about the result of the
  *            method invocation.
@@ -5791,7 +5791,7 @@ g_dbus_connection_call_with_unix_fd_list (GDBusConnection        *connection,
 /**
  * g_dbus_connection_call_with_unix_fd_list_finish:
  * @connection: A #GDBusConnection.
- * @out_fd_list: (out): Return location for a #GUnixFDList or %NULL.
+ * @out_fd_list: (out) (allow-none): Return location for a #GUnixFDList or %NULL.
  * @res: A #GAsyncResult obtained from the #GAsyncReadyCallback passed to g_dbus_connection_call_with_unix_fd_list().
  * @error: Return location for error or %NULL.
  *
@@ -5825,8 +5825,8 @@ g_dbus_connection_call_with_unix_fd_list_finish (GDBusConnection  *connection,
  * @timeout_msec: The timeout in milliseconds, -1 to use the default
  *                timeout or %G_MAXINT for no timeout.
  * @fd_list: (allow-none): A #GUnixFDList or %NULL.
- * @out_fd_list: (out): Return location for a #GUnixFDList or %NULL.
- * @cancellable: A #GCancellable or %NULL.
+ * @out_fd_list: (out) (allow-none): Return location for a #GUnixFDList or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @error: Return location for error or %NULL.
  *
  * Like g_dbus_connection_call_sync() but also takes and returns #GUnixFDList objects.
@@ -6771,7 +6771,7 @@ get_uninitialized_connection (GBusType       bus_type,
 /**
  * g_bus_get_sync:
  * @bus_type: A #GBusType.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @error: Return location for error or %NULL.
  *
  * Synchronously connects to the message bus specified by @bus_type.
@@ -6848,7 +6848,7 @@ bus_get_async_initable_cb (GObject      *source_object,
 /**
  * g_bus_get:
  * @bus_type: A #GBusType.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @callback: A #GAsyncReadyCallback to call when the request is satisfied.
  * @user_data: The data to pass to @callback.
  *
diff --git a/gio/gdbuserror.c b/gio/gdbuserror.c
index 946670a7e..9e1c50f89 100644
--- a/gio/gdbuserror.c
+++ b/gio/gdbuserror.c
@@ -650,7 +650,7 @@ g_dbus_error_new_for_dbus_error (const gchar *dbus_error_name,
  * @error: A pointer to a #GError or %NULL.
  * @dbus_error_name: D-Bus error name.
  * @dbus_error_message: D-Bus error message.
- * @format: printf()-style format to prepend to @dbus_error_message or %NULL.
+ * @format: (allow-none): printf()-style format to prepend to @dbus_error_message or %NULL.
  * @...: Arguments for @format.
  *
  * Does nothing if @error is %NULL. Otherwise sets *@error to
@@ -695,7 +695,7 @@ g_dbus_error_set_dbus_error (GError      **error,
  * @error: A pointer to a #GError or %NULL.
  * @dbus_error_name: D-Bus error name.
  * @dbus_error_message: D-Bus error message.
- * @format: printf()-style format to prepend to @dbus_error_message or %NULL.
+ * @format: (allow-none): printf()-style format to prepend to @dbus_error_message or %NULL.
  * @var_args: Arguments for @format.
  *
  * Like g_dbus_error_set_dbus_error() but intended for language bindings.
diff --git a/gio/gdbusinterface.c b/gio/gdbusinterface.c
index d1af07d83..14f1326a0 100644
--- a/gio/gdbusinterface.c
+++ b/gio/gdbusinterface.c
@@ -124,7 +124,7 @@ g_dbus_interface_dup_object (GDBusInterface *interface_)
 /**
  * g_dbus_interface_set_object:
  * @interface_: An exported D-Bus interface.
- * @object: A #GDBusObject or %NULL.
+ * @object: (allow-none): A #GDBusObject or %NULL.
  *
  * Sets the #GDBusObject for @interface_ to @object.
  *
diff --git a/gio/gdbusintrospection.c b/gio/gdbusintrospection.c
index a9c7f1cf3..a97fa43c1 100644
--- a/gio/gdbusintrospection.c
+++ b/gio/gdbusintrospection.c
@@ -1838,7 +1838,7 @@ g_dbus_node_info_new_for_xml (const gchar  *xml_data,
 
 /**
  * g_dbus_annotation_info_lookup:
- * @annotations: (array zero-terminated=1): A %NULL-terminated array of annotations or %NULL.
+ * @annotations: (array zero-terminated=1) (allow-none): A %NULL-terminated array of annotations or %NULL.
  * @name: The name of the annotation to look up.
  *
  * Looks up the value of an annotation.
diff --git a/gio/gdbusmessage.c b/gio/gdbusmessage.c
index 4c968f5bb..ca7f6c5c5 100644
--- a/gio/gdbusmessage.c
+++ b/gio/gdbusmessage.c
@@ -218,9 +218,9 @@ g_dbus_message_new (void)
 
 /**
  * g_dbus_message_new_method_call:
- * @name: A valid D-Bus name or %NULL.
+ * @name: (allow-none): A valid D-Bus name or %NULL.
  * @path: A valid object path.
- * @interface_: A valid D-Bus interface name or %NULL.
+ * @interface_: (allow-none): A valid D-Bus interface name or %NULL.
  * @method: A valid method name.
  *
  * Creates a new #GDBusMessage for a method call.
@@ -636,7 +636,7 @@ g_dbus_message_get_header (GDBusMessage             *message,
  * g_dbus_message_set_header:
  * @message: A #GDBusMessage.
  * @header_field: A 8-bit unsigned integer (typically a value from the #GDBusMessageHeaderField enumeration)
- * @value: A #GVariant to set the header field or %NULL to clear the header field.
+ * @value: (allow-none): A #GVariant to set the header field or %NULL to clear the header field.
  *
  * Sets a header field on @message.
  *
diff --git a/gio/gdbusmethodinvocation.c b/gio/gdbusmethodinvocation.c
index be3dc5633..18e366d84 100644
--- a/gio/gdbusmethodinvocation.c
+++ b/gio/gdbusmethodinvocation.c
@@ -286,11 +286,11 @@ g_dbus_method_invocation_get_user_data (GDBusMethodInvocation *invocation)
 
 /* < internal >
  * _g_dbus_method_invocation_new:
- * @sender: The bus name that invoked the method or %NULL if @connection is not a bus connection.
+ * @sender: (allow-none): The bus name that invoked the method or %NULL if @connection is not a bus connection.
  * @object_path: The object path the method was invoked on.
  * @interface_name: The name of the D-Bus interface the method was invoked on.
  * @method_name: The name of the method that was invoked.
- * @method_info: Information about the method call or %NULL.
+ * @method_info: (allow-none): Information about the method call or %NULL.
  * @connection: The #GDBusConnection the method was invoked on.
  * @message: The D-Bus message as a #GDBusMessage.
  * @parameters: The parameters as a #GVariant tuple.
diff --git a/gio/gdbusnameowning.c b/gio/gdbusnameowning.c
index 207fa60b9..260b08843 100644
--- a/gio/gdbusnameowning.c
+++ b/gio/gdbusnameowning.c
@@ -495,10 +495,10 @@ connection_get_cb (GObject      *source_object,
  * @connection: A #GDBusConnection.
  * @name: The well-known name to own.
  * @flags: A set of flags from the #GBusNameOwnerFlags enumeration.
- * @name_acquired_handler: Handler to invoke when @name is acquired or %NULL.
- * @name_lost_handler: Handler to invoke when @name is lost or %NULL.
+ * @name_acquired_handler: (allow-none): Handler to invoke when @name is acquired or %NULL.
+ * @name_lost_handler: (allow-none): Handler to invoke when @name is lost or %NULL.
  * @user_data: User data to pass to handlers.
- * @user_data_free_func: Function for freeing @user_data or %NULL.
+ * @user_data_free_func: (allow-none): Function for freeing @user_data or %NULL.
  *
  * Like g_bus_own_name() but takes a #GDBusConnection instead of a
  * #GBusType.
@@ -557,11 +557,11 @@ g_bus_own_name_on_connection (GDBusConnection          *connection,
  * @bus_type: The type of bus to own a name on.
  * @name: The well-known name to own.
  * @flags: A set of flags from the #GBusNameOwnerFlags enumeration.
- * @bus_acquired_handler: Handler to invoke when connected to the bus of type @bus_type or %NULL.
- * @name_acquired_handler: Handler to invoke when @name is acquired or %NULL.
- * @name_lost_handler: Handler to invoke when @name is lost or %NULL.
+ * @bus_acquired_handler: (allow-none): Handler to invoke when connected to the bus of type @bus_type or %NULL.
+ * @name_acquired_handler: (allow-none): Handler to invoke when @name is acquired or %NULL.
+ * @name_lost_handler: (allow-none): Handler to invoke when @name is lost or %NULL.
  * @user_data: User data to pass to handlers.
- * @user_data_free_func: Function for freeing @user_data or %NULL.
+ * @user_data_free_func: (allow-none): Function for freeing @user_data or %NULL.
  *
  * Starts acquiring @name on the bus specified by @bus_type and calls
  * @name_acquired_handler and @name_lost_handler when the name is
diff --git a/gio/gdbusnamewatching.c b/gio/gdbusnamewatching.c
index bdda901e5..12e8ed762 100644
--- a/gio/gdbusnamewatching.c
+++ b/gio/gdbusnamewatching.c
@@ -505,10 +505,10 @@ connection_get_cb (GObject      *source_object,
  * @bus_type: The type of bus to watch a name on.
  * @name: The name (well-known or unique) to watch.
  * @flags: Flags from the #GBusNameWatcherFlags enumeration.
- * @name_appeared_handler: Handler to invoke when @name is known to exist or %NULL.
- * @name_vanished_handler: Handler to invoke when @name is known to not exist or %NULL.
+ * @name_appeared_handler: (allow-none): Handler to invoke when @name is known to exist or %NULL.
+ * @name_vanished_handler: (allow-none): Handler to invoke when @name is known to not exist or %NULL.
  * @user_data: User data to pass to handlers.
- * @user_data_free_func: Function for freeing @user_data or %NULL.
+ * @user_data_free_func: (allow-none): Function for freeing @user_data or %NULL.
  *
  * Starts watching @name on the bus specified by @bus_type and calls
  * @name_appeared_handler and @name_vanished_handler when the name is
@@ -594,10 +594,10 @@ g_bus_watch_name (GBusType                  bus_type,
  * @connection: A #GDBusConnection.
  * @name: The name (well-known or unique) to watch.
  * @flags: Flags from the #GBusNameWatcherFlags enumeration.
- * @name_appeared_handler: Handler to invoke when @name is known to exist or %NULL.
- * @name_vanished_handler: Handler to invoke when @name is known to not exist or %NULL.
+ * @name_appeared_handler: (allow-none): Handler to invoke when @name is known to exist or %NULL.
+ * @name_vanished_handler: (allow-none): Handler to invoke when @name is known to not exist or %NULL.
  * @user_data: User data to pass to handlers.
- * @user_data_free_func: Function for freeing @user_data or %NULL.
+ * @user_data_free_func: (allow-none): Function for freeing @user_data or %NULL.
  *
  * Like g_bus_watch_name() but takes a #GDBusConnection instead of a
  * #GBusType.
diff --git a/gio/gdbusobjectmanagerclient.c b/gio/gdbusobjectmanagerclient.c
index aeff7e41c..a207104c1 100644
--- a/gio/gdbusobjectmanagerclient.c
+++ b/gio/gdbusobjectmanagerclient.c
@@ -587,10 +587,10 @@ g_dbus_object_manager_client_init (GDBusObjectManagerClient *manager)
  * @flags: Zero or more flags from the #GDBusObjectManagerClientFlags enumeration.
  * @name: The owner of the control object (unique or well-known name).
  * @object_path: The object path of the control object.
- * @get_proxy_type_func: A #GDBusProxyTypeFunc function or %NULL to always construct #GDBusProxy proxies.
+ * @get_proxy_type_func: (allow-none): A #GDBusProxyTypeFunc function or %NULL to always construct #GDBusProxy proxies.
  * @get_proxy_type_user_data: User data to pass to @get_proxy_type_func.
  * @get_proxy_type_destroy_notify: (allow-none): Free function for @get_proxy_type_user_data or %NULL.
- * @cancellable: A #GCancellable or %NULL
+ * @cancellable: (allow-none): A #GCancellable or %NULL
  * @error: Return location for error or %NULL.
  *
  * Creates a new #GDBusObjectManagerClient object.
@@ -647,10 +647,10 @@ g_dbus_object_manager_client_new_sync (GDBusConnection               *connection
  * @flags: Zero or more flags from the #GDBusObjectManagerClientFlags enumeration.
  * @name: The owner of the control object (unique or well-known name).
  * @object_path: The object path of the control object.
- * @get_proxy_type_func: A #GDBusProxyTypeFunc function or %NULL to always construct #GDBusProxy proxies.
+ * @get_proxy_type_func: (allow-none): A #GDBusProxyTypeFunc function or %NULL to always construct #GDBusProxy proxies.
  * @get_proxy_type_user_data: User data to pass to @get_proxy_type_func.
  * @get_proxy_type_destroy_notify: (allow-none): Free function for @get_proxy_type_user_data or %NULL.
- * @cancellable: A #GCancellable or %NULL
+ * @cancellable: (allow-none): A #GCancellable or %NULL
  * @callback: A #GAsyncReadyCallback to call when the request is satisfied.
  * @user_data: The data to pass to @callback.
  *
@@ -739,10 +739,10 @@ g_dbus_object_manager_client_new_finish (GAsyncResult   *res,
  * @flags: Zero or more flags from the #GDBusObjectManagerClientFlags enumeration.
  * @name: The owner of the control object (unique or well-known name).
  * @object_path: The object path of the control object.
- * @get_proxy_type_func: A #GDBusProxyTypeFunc function or %NULL to always construct #GDBusProxy proxies.
+ * @get_proxy_type_func: (allow-none): A #GDBusProxyTypeFunc function or %NULL to always construct #GDBusProxy proxies.
  * @get_proxy_type_user_data: User data to pass to @get_proxy_type_func.
  * @get_proxy_type_destroy_notify: (allow-none): Free function for @get_proxy_type_user_data or %NULL.
- * @cancellable: A #GCancellable or %NULL
+ * @cancellable: (allow-none): A #GCancellable or %NULL
  * @error: Return location for error or %NULL.
  *
  * Like g_dbus_object_manager_client_new_sync() but takes a #GBusType instead
@@ -799,10 +799,10 @@ g_dbus_object_manager_client_new_for_bus_sync (GBusType                       bu
  * @flags: Zero or more flags from the #GDBusObjectManagerClientFlags enumeration.
  * @name: The owner of the control object (unique or well-known name).
  * @object_path: The object path of the control object.
- * @get_proxy_type_func: A #GDBusProxyTypeFunc function or %NULL to always construct #GDBusProxy proxies.
+ * @get_proxy_type_func: (allow-none): A #GDBusProxyTypeFunc function or %NULL to always construct #GDBusProxy proxies.
  * @get_proxy_type_user_data: User data to pass to @get_proxy_type_func.
  * @get_proxy_type_destroy_notify: (allow-none): Free function for @get_proxy_type_user_data or %NULL.
- * @cancellable: A #GCancellable or %NULL
+ * @cancellable: (allow-none): A #GCancellable or %NULL
  * @callback: A #GAsyncReadyCallback to call when the request is satisfied.
  * @user_data: The data to pass to @callback.
  *
diff --git a/gio/gdbusproxy.c b/gio/gdbusproxy.c
index ed46935df..5bab9bfbb 100644
--- a/gio/gdbusproxy.c
+++ b/gio/gdbusproxy.c
@@ -612,7 +612,7 @@ g_dbus_proxy_class_init (GDBusProxyClass *klass)
   /**
    * GDBusProxy::g-signal:
    * @proxy: The #GDBusProxy emitting the signal.
-   * @sender_name: The sender of the signal or %NULL if the connection is not a bus connection.
+   * @sender_name: (allow-none): The sender of the signal or %NULL if the connection is not a bus connection.
    * @signal_name: The name of the signal.
    * @parameters: A #GVariant tuple with parameters for the signal.
    *
@@ -2007,7 +2007,7 @@ initable_iface_init (GInitableIface *initable_iface)
  * @name: (allow-none): A bus name (well-known or unique) or %NULL if @connection is not a message bus connection.
  * @object_path: An object path.
  * @interface_name: A D-Bus interface name.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @callback: Callback function to invoke when the proxy is ready.
  * @user_data: User data to pass to @callback.
  *
@@ -2177,7 +2177,7 @@ g_dbus_proxy_new_sync (GDBusConnection     *connection,
  * @name: A bus name (well-known or unique).
  * @object_path: An object path.
  * @interface_name: A D-Bus interface name.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @callback: Callback function to invoke when the proxy is ready.
  * @user_data: User data to pass to @callback.
  *
@@ -2243,7 +2243,7 @@ g_dbus_proxy_new_for_bus_finish (GAsyncResult  *res,
  * @name: A bus name (well-known or unique).
  * @object_path: An object path.
  * @interface_name: A D-Bus interface name.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @error: Return location for error or %NULL.
  *
  * Like g_dbus_proxy_new_sync() but takes a #GBusType instead of a #GDBusConnection.
@@ -2936,8 +2936,8 @@ g_dbus_proxy_call_sync_internal (GDBusProxy      *proxy,
  * @flags: Flags from the #GDBusCallFlags enumeration.
  * @timeout_msec: The timeout in milliseconds (with %G_MAXINT meaning
  *                "infinite") or -1 to use the proxy default timeout.
- * @cancellable: A #GCancellable or %NULL.
- * @callback: A #GAsyncReadyCallback to call when the request is satisfied or %NULL if you don't
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
+ * @callback: (allow-none): A #GAsyncReadyCallback to call when the request is satisfied or %NULL if you don't
  * care about the result of the method invocation.
  * @user_data: The data to pass to @callback.
  *
@@ -3029,7 +3029,7 @@ g_dbus_proxy_call_finish (GDBusProxy    *proxy,
  * @flags: Flags from the #GDBusCallFlags enumeration.
  * @timeout_msec: The timeout in milliseconds (with %G_MAXINT meaning
  *                "infinite") or -1 to use the proxy default timeout.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @error: Return location for error or %NULL.
  *
  * Synchronously invokes the @method_name method on @proxy.
@@ -3097,8 +3097,8 @@ g_dbus_proxy_call_sync (GDBusProxy      *proxy,
  * @timeout_msec: The timeout in milliseconds (with %G_MAXINT meaning
  *                "infinite") or -1 to use the proxy default timeout.
  * @fd_list: (allow-none): A #GUnixFDList or %NULL.
- * @cancellable: A #GCancellable or %NULL.
- * @callback: A #GAsyncReadyCallback to call when the request is satisfied or %NULL if you don't
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
+ * @callback: (allow-none): A #GAsyncReadyCallback to call when the request is satisfied or %NULL if you don't
  * care about the result of the method invocation.
  * @user_data: The data to pass to @callback.
  *
@@ -3125,7 +3125,7 @@ g_dbus_proxy_call_with_unix_fd_list (GDBusProxy          *proxy,
 /**
  * g_dbus_proxy_call_with_unix_fd_list_finish:
  * @proxy: A #GDBusProxy.
- * @out_fd_list: (out): Return location for a #GUnixFDList or %NULL.
+ * @out_fd_list: (out) (allow-none): Return location for a #GUnixFDList or %NULL.
  * @res: A #GAsyncResult obtained from the #GAsyncReadyCallback passed to g_dbus_proxy_call_with_unix_fd_list().
  * @error: Return location for error or %NULL.
  *
@@ -3155,8 +3155,8 @@ g_dbus_proxy_call_with_unix_fd_list_finish (GDBusProxy    *proxy,
  * @timeout_msec: The timeout in milliseconds (with %G_MAXINT meaning
  *                "infinite") or -1 to use the proxy default timeout.
  * @fd_list: (allow-none): A #GUnixFDList or %NULL.
- * @out_fd_list: (out): Return location for a #GUnixFDList or %NULL.
- * @cancellable: A #GCancellable or %NULL.
+ * @out_fd_list: (out) (allow-none): Return location for a #GUnixFDList or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @error: Return location for error or %NULL.
  *
  * Like g_dbus_proxy_call_sync() but also takes and returns #GUnixFDList objects.
diff --git a/gio/gdbusserver.c b/gio/gdbusserver.c
index 7dde45305..5e7dd85fa 100644
--- a/gio/gdbusserver.c
+++ b/gio/gdbusserver.c
@@ -448,7 +448,7 @@ on_run (GSocketService    *service,
  * @flags: Flags from the #GDBusServerFlags enumeration.
  * @guid: A D-Bus GUID.
  * @observer: (allow-none): A #GDBusAuthObserver or %NULL.
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
  * @error: Return location for server or %NULL.
  *
  * Creates a new D-Bus server that listens on the first address in
diff --git a/gio/gfile.c b/gio/gfile.c
index 306d014c0..7e963ca05 100644
--- a/gio/gfile.c
+++ b/gio/gfile.c
@@ -887,7 +887,7 @@ g_file_enumerate_children (GFile                *file,
  * @io_priority: the <link linkend="io-priority">I/O priority</link> 
  *     of the request.
  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
- * @callback: (scope async): a #GAsyncReadyCallback to call when the
+ * @callback: (scope async) : a #GAsyncReadyCallback to call when the
  *     request is satisfied
  * @user_data: (closure): the data to pass to callback function
  *
@@ -4235,7 +4235,7 @@ g_file_set_attribute_int64 (GFile                *file,
  * @flags: flags affecting the operation
  * @mount_operation: (allow-none): a #GMountOperation, or %NULL to avoid user interaction.
  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
- * @callback: (scope async): a #GAsyncReadyCallback to call when the request is satisfied, or %NULL.
+ * @callback: (scope async) (allow-none): a #GAsyncReadyCallback to call when the request is satisfied, or %NULL.
  * @user_data: (closure): the data to pass to callback function
  * 
  * Mounts a file of type G_FILE_TYPE_MOUNTABLE.
@@ -4322,7 +4322,7 @@ g_file_mount_mountable_finish (GFile         *file,
  * @file: input #GFile.
  * @flags: flags affecting the operation
  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
- * @callback: (scope async): a #GAsyncReadyCallback to call when the request is satisfied, or %NULL.
+ * @callback: (scope async) (allow-none): a #GAsyncReadyCallback to call when the request is satisfied, or %NULL.
  * @user_data: (closure): the data to pass to callback function
  *
  * Unmounts a file of type G_FILE_TYPE_MOUNTABLE.
@@ -4410,7 +4410,7 @@ g_file_unmount_mountable_finish (GFile         *file,
  * @flags: flags affecting the operation
  * @mount_operation: (allow-none): a #GMountOperation, or %NULL to avoid user interaction.
  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
- * @callback: (scope async): a #GAsyncReadyCallback to call when the request is satisfied, or %NULL.
+ * @callback: (scope async) (allow-none): a #GAsyncReadyCallback to call when the request is satisfied, or %NULL.
  * @user_data: (closure): the data to pass to callback function
  *
  * Unmounts a file of type G_FILE_TYPE_MOUNTABLE.
@@ -4509,7 +4509,7 @@ g_file_unmount_mountable_with_operation_finish (GFile         *file,
  * @file: input #GFile.
  * @flags: flags affecting the operation
  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
- * @callback: (scope async): a #GAsyncReadyCallback to call when the request is satisfied, or %NULL.
+ * @callback: (scope async) (allow-none): a #GAsyncReadyCallback to call when the request is satisfied, or %NULL.
  * @user_data: (closure): the data to pass to callback function
  * 
  * Starts an asynchronous eject on a mountable.  
@@ -4595,7 +4595,7 @@ g_file_eject_mountable_finish (GFile         *file,
  * @flags: flags affecting the operation
  * @mount_operation: (allow-none): a #GMountOperation, or %NULL to avoid user interaction.
  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
- * @callback: (scope async): a #GAsyncReadyCallback to call when the request is satisfied, or %NULL.
+ * @callback: (scope async) (allow-none): a #GAsyncReadyCallback to call when the request is satisfied, or %NULL.
  * @user_data: (closure): the data to pass to callback function
  *
  * Starts an asynchronous eject on a mountable.
@@ -6032,7 +6032,7 @@ g_file_new_for_commandline_arg (const char *arg)
  * @flags: flags affecting the operation
  * @mount_operation: (allow-none): a #GMountOperation or %NULL to avoid user interaction.
  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
- * @callback: a #GAsyncReadyCallback to call when the request is satisfied, or %NULL.
+ * @callback: (allow-none): a #GAsyncReadyCallback to call when the request is satisfied, or %NULL.
  * @user_data: the data to pass to callback function
  * 
  * Starts a @mount_operation, mounting the volume that contains the file @location. 
@@ -6967,8 +6967,8 @@ g_file_replace_contents_finish (GFile         *file,
  * @file: input #GFile.
  * @flags: flags affecting the operation
  * @start_operation: (allow-none): a #GMountOperation, or %NULL to avoid user interaction.
- * @cancellable: optional #GCancellable object, %NULL to ignore.
- * @callback: a #GAsyncReadyCallback to call when the request is satisfied, or %NULL.
+ * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
+ * @callback: (allow-none): a #GAsyncReadyCallback to call when the request is satisfied, or %NULL.
  * @user_data: the data to pass to callback function
  *
  * Starts a file of type G_FILE_TYPE_MOUNTABLE.
@@ -7059,8 +7059,8 @@ g_file_start_mountable_finish (GFile                      *file,
  * @file: input #GFile.
  * @flags: flags affecting the operation
  * @mount_operation: (allow-none): a #GMountOperation, or %NULL to avoid user interaction.
- * @cancellable: optional #GCancellable object, %NULL to ignore.
- * @callback: a #GAsyncReadyCallback to call when the request is satisfied, or %NULL.
+ * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
+ * @callback: (allow-none): a #GAsyncReadyCallback to call when the request is satisfied, or %NULL.
  * @user_data: the data to pass to callback function
  *
  * Stops a file of type G_FILE_TYPE_MOUNTABLE.
@@ -7148,7 +7148,7 @@ g_file_stop_mountable_finish (GFile                      *file,
  * g_file_poll_mountable:
  * @file: input #GFile.
  * @cancellable: optional #GCancellable object, %NULL to ignore.
- * @callback: a #GAsyncReadyCallback to call when the request is satisfied, or %NULL.
+ * @callback: (allow-none): a #GAsyncReadyCallback to call when the request is satisfied, or %NULL.
  * @user_data: the data to pass to callback function
  *
  * Polls a file of type G_FILE_TYPE_MOUNTABLE.
diff --git a/gio/ginitable.c b/gio/ginitable.c
index b68e5c81a..e3c81f185 100644
--- a/gio/ginitable.c
+++ b/gio/ginitable.c
@@ -121,7 +121,7 @@ g_initable_init (GInitable     *initable,
  * @cancellable: optional #GCancellable object, %NULL to ignore.
  * @error: a #GError location to store the error occurring, or %NULL to
  *    ignore.
- * @first_property_name: the name of the first property, or %NULL if no
+ * @first_property_name: (allow-none): the name of the first property, or %NULL if no
  *     properties
  * @...:  the value if the first property, followed by and other property
  *    value pairs, and ended by %NULL.
diff --git a/gio/gioscheduler.c b/gio/gioscheduler.c
index 36db5f256..e91ecdedd 100644
--- a/gio/gioscheduler.c
+++ b/gio/gioscheduler.c
@@ -188,7 +188,7 @@ io_job_thread (gpointer data,
  * g_io_scheduler_push_job:
  * @job_func: a #GIOSchedulerJobFunc.
  * @user_data: data to pass to @job_func
- * @notify: a #GDestroyNotify for @user_data, or %NULL
+ * @notify: (allow-none): a #GDestroyNotify for @user_data, or %NULL
  * @io_priority: the <link linkend="gioscheduler">I/O priority</link> 
  * of the request.
  * @cancellable: optional #GCancellable object, %NULL to ignore.
@@ -309,7 +309,7 @@ mainloop_proxy_free (MainLoopProxy *proxy)
  * @job: a #GIOSchedulerJob
  * @func: a #GSourceFunc callback that will be called in the original thread
  * @user_data: data to pass to @func
- * @notify: a #GDestroyNotify for @user_data, or %NULL
+ * @notify: (allow-none): a #GDestroyNotify for @user_data, or %NULL
  * 
  * Used from an I/O job to send a callback to be run in the thread
  * that the job was started from, waiting for the result (and thus
@@ -361,7 +361,7 @@ g_io_scheduler_job_send_to_mainloop (GIOSchedulerJob *job,
  * @job: a #GIOSchedulerJob
  * @func: a #GSourceFunc callback that will be called in the original thread
  * @user_data: data to pass to @func
- * @notify: a #GDestroyNotify for @user_data, or %NULL
+ * @notify: (allow-none): a #GDestroyNotify for @user_data, or %NULL
  * 
  * Used from an I/O job to send a callback to be run asynchronously in
  * the thread that the job was started from. The callback will be run
diff --git a/gio/gmemoryoutputstream.c b/gio/gmemoryoutputstream.c
index 182d2dead..08b4fba6b 100644
--- a/gio/gmemoryoutputstream.c
+++ b/gio/gmemoryoutputstream.c
@@ -329,11 +329,11 @@ g_memory_output_stream_init (GMemoryOutputStream *stream)
 
 /**
  * g_memory_output_stream_new: (skip)
- * @data: pointer to a chunk of memory to use, or %NULL
+ * @data: (allow-none): pointer to a chunk of memory to use, or %NULL
  * @size: the size of @data
- * @realloc_function: a function with realloc() semantics (like g_realloc())
+ * @realloc_function: (allow-none): a function with realloc() semantics (like g_realloc())
  *     to be called when @data needs to be grown, or %NULL
- * @destroy_function: a function to be called on @data when the stream is
+ * @destroy_function: (allow-none): a function to be called on @data when the stream is
  *     finalized, or %NULL
  *
  * Creates a new #GMemoryOutputStream.
diff --git a/gio/gnetworkmonitor.c b/gio/gnetworkmonitor.c
index 9afc42176..f3359ef1d 100644
--- a/gio/gnetworkmonitor.c
+++ b/gio/gnetworkmonitor.c
@@ -104,7 +104,7 @@ g_network_monitor_get_network_available (GNetworkMonitor *monitor)
  * g_network_monitor_can_reach:
  * @monitor: a #GNetworkMonitor
  * @connectable: a #GSocketConnectable
- * @cancellable: a #GCancellable, or %NULL
+ * @cancellable: (allow-none): a #GCancellable, or %NULL
  * @error: return location for a #GError, or %NULL
  *
  * Attempts to determine whether or not the host pointed to by
@@ -166,7 +166,7 @@ g_network_monitor_real_can_reach_async (GNetworkMonitor     *monitor,
  * g_network_monitor_can_reach_async:
  * @monitor: a #GNetworkMonitor
  * @connectable: a #GSocketConnectable
- * @cancellable: a #GCancellable, or %NULL
+ * @cancellable: (allow-none): a #GCancellable, or %NULL
  * @callback: (scope async): a #GAsyncReadyCallback to call when the
  *     request is satisfied
  * @user_data: (closure): the data to pass to callback function
diff --git a/gio/gpermission.c b/gio/gpermission.c
index aefccaad2..422fb12ce 100644
--- a/gio/gpermission.c
+++ b/gio/gpermission.c
@@ -74,7 +74,7 @@ enum  {
 /**
  * g_permission_acquire:
  * @permission: a #GPermission instance
- * @cancellable: a #GCancellable, or %NULL
+ * @cancellable: (allow-none): a #GCancellable, or %NULL
  * @error: a pointer to a %NULL #GError, or %NULL
  *
  * Attempts to acquire the permission represented by @permission.
@@ -109,7 +109,7 @@ g_permission_acquire (GPermission   *permission,
 /**
  * g_permission_acquire_async:
  * @permission: a #GPermission instance
- * @cancellable: a #GCancellable, or %NULL
+ * @cancellable: (allow-none): a #GCancellable, or %NULL
  * @callback: the #GAsyncReadyCallback to call when done
  * @user_data: the user data to pass to @callback
  *
@@ -158,7 +158,7 @@ g_permission_acquire_finish (GPermission   *permission,
 /**
  * g_permission_release:
  * @permission: a #GPermission instance
- * @cancellable: a #GCancellable, or %NULL
+ * @cancellable: (allow-none): a #GCancellable, or %NULL
  * @error: a pointer to a %NULL #GError, or %NULL
  *
  * Attempts to release the permission represented by @permission.
@@ -193,7 +193,7 @@ g_permission_release (GPermission   *permission,
 /**
  * g_permission_release_async:
  * @permission: a #GPermission instance
- * @cancellable: a #GCancellable, or %NULL
+ * @cancellable: (allow-none): a #GCancellable, or %NULL
  * @callback: the #GAsyncReadyCallback to call when done
  * @user_data: the user data to pass to @callback
  *
diff --git a/gio/gsettingsbackend.c b/gio/gsettingsbackend.c
index f2f11eb5d..c89531ad3 100644
--- a/gio/gsettingsbackend.c
+++ b/gio/gsettingsbackend.c
@@ -177,7 +177,7 @@ g_settings_backend_watch_weak_notify (gpointer  data,
  * g_settings_backend_watch:
  * @backend: a #GSettingsBackend
  * @target: the GObject (typically GSettings instance) to call back to
- * @context: a #GMainContext, or %NULL
+ * @context: (allow-none): a #GMainContext, or %NULL
  * ...: callbacks...
  *
  * Registers a new watch on a #GSettingsBackend.
diff --git a/gio/gsimpleasyncresult.c b/gio/gsimpleasyncresult.c
index 7ab2cd2db..1b951194c 100644
--- a/gio/gsimpleasyncresult.c
+++ b/gio/gsimpleasyncresult.c
@@ -1061,7 +1061,7 @@ g_simple_async_report_take_gerror_in_idle (GObject *object,
 /**
  * g_simple_async_result_set_check_cancellable:
  * @simple: a #GSimpleAsyncResult
- * @check_cancellable: a #GCancellable to check, or %NULL to unset
+ * @check_cancellable: (allow-none): a #GCancellable to check, or %NULL to unset
  *
  * Sets a #GCancellable to check before dispatching results.
  *
diff --git a/gio/gsocket.c b/gio/gsocket.c
index a28546f32..0fa133fe8 100644
--- a/gio/gsocket.c
+++ b/gio/gsocket.c
@@ -2695,7 +2695,7 @@ g_socket_send_with_blocking (GSocket       *socket,
 /**
  * g_socket_send_to:
  * @socket: a #GSocket
- * @address: a #GSocketAddress, or %NULL
+ * @address: (allow-none): a #GSocketAddress, or %NULL
  * @buffer: (array length=size) (element-type guint8): the buffer
  *     containing the data to send.
  * @size: the number of bytes to send
@@ -3584,7 +3584,7 @@ g_socket_condition_timed_wait (GSocket       *socket,
 /**
  * g_socket_send_message:
  * @socket: a #GSocket
- * @address: a #GSocketAddress, or %NULL
+ * @address: (allow-none): a #GSocketAddress, or %NULL
  * @vectors: (array length=num_vectors): an array of #GOutputVector structs
  * @num_vectors: the number of elements in @vectors, or -1
  * @messages: (array length=num_messages) (allow-none): a pointer to an
diff --git a/gio/gsocketclient.c b/gio/gsocketclient.c
index d24694760..63c26aa90 100644
--- a/gio/gsocketclient.c
+++ b/gio/gsocketclient.c
@@ -482,7 +482,7 @@ g_socket_client_get_local_address (GSocketClient *client)
 /**
  * g_socket_client_set_local_address:
  * @client: a #GSocketClient.
- * @address: a #GSocketAddress, or %NULL
+ * @address: (allow-none): a #GSocketAddress, or %NULL
  *
  * Sets the local address of the socket client.
  * The sockets created by this object will bound to the
diff --git a/gio/gtlsconnection.c b/gio/gtlsconnection.c
index 5e66dd1b6..7d33e3739 100644
--- a/gio/gtlsconnection.c
+++ b/gio/gtlsconnection.c
@@ -730,7 +730,7 @@ g_tls_connection_get_rehandshake_mode (GTlsConnection       *conn)
 /**
  * g_tls_connection_handshake:
  * @conn: a #GTlsConnection
- * @cancellable: a #GCancellable, or %NULL
+ * @cancellable: (allow-none): a #GCancellable, or %NULL
  * @error: a #GError, or %NULL
  *
  * Attempts a TLS handshake on @conn.
@@ -775,7 +775,7 @@ g_tls_connection_handshake (GTlsConnection   *conn,
  * @conn: a #GTlsConnection
  * @io_priority: the <link linkend="io-priority">I/O priority</link>
  * of the request.
- * @cancellable: a #GCancellable, or %NULL
+ * @cancellable: (allow-none): a #GCancellable, or %NULL
  * @callback: callback to call when the handshake is complete
  * @user_data: the data to pass to the callback function
  *
diff --git a/gio/gvolume.c b/gio/gvolume.c
index d932d0830..97f9485c3 100644
--- a/gio/gvolume.c
+++ b/gio/gvolume.c
@@ -454,7 +454,7 @@ g_volume_eject_finish (GVolume       *volume,
  * @mount_operation: (allow-none): a #GMountOperation or %NULL to
  *     avoid user interaction.
  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
- * @callback: a #GAsyncReadyCallback, or %NULL.
+ * @callback: (allow-none): a #GAsyncReadyCallback, or %NULL.
  * @user_data: user data passed to @callback.
  *
  * Ejects a volume. This is an asynchronous operation, and is
diff --git a/glib/garray.c b/glib/garray.c
index 567774c95..0cb3713a5 100644
--- a/glib/garray.c
+++ b/glib/garray.c
@@ -897,7 +897,7 @@ g_ptr_array_sized_new (guint reserved_size)
 
 /**
  * g_ptr_array_new_with_free_func:
- * @element_free_func: A function to free elements with destroy @array or %NULL.
+ * @element_free_func: (allow-none): A function to free elements with destroy @array or %NULL.
  *
  * Creates a new #GPtrArray with a reference count of 1 and use @element_free_func
  * for freeing each element when the array is destroyed either via
@@ -921,7 +921,7 @@ g_ptr_array_new_with_free_func (GDestroyNotify element_free_func)
 /**
  * g_ptr_array_new_full:
  * @reserved_size: number of pointers preallocated.
- * @element_free_func: A function to free elements with destroy @array or %NULL.
+ * @element_free_func: (allow-none): A function to free elements with destroy @array or %NULL.
  *
  * Creates a new #GPtrArray with @reserved_size pointers preallocated
  * and a reference count of 1. This avoids frequent reallocation, if
@@ -949,7 +949,7 @@ g_ptr_array_new_full (guint          reserved_size,
 /**
  * g_ptr_array_set_free_func:
  * @array: A #GPtrArray.
- * @element_free_func: A function to free elements with destroy @array or %NULL.
+ * @element_free_func: (allow-none): A function to free elements with destroy @array or %NULL.
  *
  * Sets a function for freeing each element when @array is destroyed
  * either via g_ptr_array_unref(), when g_ptr_array_free() is called
diff --git a/glib/gbookmarkfile.c b/glib/gbookmarkfile.c
index 5b5ff5020..edf196bde 100644
--- a/glib/gbookmarkfile.c
+++ b/glib/gbookmarkfile.c
@@ -1816,7 +1816,7 @@ find_file_in_data_dirs (const gchar   *file,
  * g_bookmark_file_load_from_data_dirs:
  * @bookmark: a #GBookmarkFile
  * @file: a relative path to a filename to open and parse
- * @full_path: return location for a string containing the full path
+ * @full_path: (allow-none): return location for a string containing the full path
  *   of the file, or %NULL
  * @error: return location for a #GError, or %NULL
  *
@@ -1897,7 +1897,7 @@ g_bookmark_file_load_from_data_dirs (GBookmarkFile  *bookmark,
 /**
  * g_bookmark_file_to_data:
  * @bookmark: a #GBookmarkFile
- * @length: return location for the length of the returned string, or %NULL
+ * @length: (allow-none): return location for the length of the returned string, or %NULL
  * @error: return location for a #GError, or %NULL
  *
  * This function outputs @bookmark as a string.
@@ -2087,7 +2087,7 @@ g_bookmark_file_has_item (GBookmarkFile *bookmark,
 /**
  * g_bookmark_file_get_uris:
  * @bookmark: a #GBookmarkFile
- * @length: return location for the number of returned URIs, or %NULL
+ * @length: (allow-none): return location for the number of returned URIs, or %NULL
  *
  * Returns all URIs of the bookmarks in the bookmark file @bookmark.
  * The array of returned URIs will be %NULL-terminated, so @length may
@@ -2131,7 +2131,7 @@ g_bookmark_file_get_uris (GBookmarkFile *bookmark,
 /**
  * g_bookmark_file_set_title:
  * @bookmark: a #GBookmarkFile
- * @uri: a valid URI or %NULL
+ * @uri: (allow-none): a valid URI or %NULL
  * @title: a UTF-8 encoded string
  *
  * Sets @title as the title of the bookmark for @uri inside the
@@ -2176,7 +2176,7 @@ g_bookmark_file_set_title (GBookmarkFile *bookmark,
 /**
  * g_bookmark_file_get_title:
  * @bookmark: a #GBookmarkFile
- * @uri: a valid URI or %NULL
+ * @uri: (allow-none): a valid URI or %NULL
  * @error: return location for a #GError, or %NULL
  *
  * Returns the title of the bookmark for @uri.
@@ -2219,7 +2219,7 @@ g_bookmark_file_get_title (GBookmarkFile  *bookmark,
 /**
  * g_bookmark_file_set_description:
  * @bookmark: a #GBookmarkFile
- * @uri: a valid URI or %NULL
+ * @uri: (allow-none): a valid URI or %NULL
  * @description: a string
  *
  * Sets @description as the description of the bookmark for @uri.
@@ -2872,7 +2872,7 @@ g_bookmark_file_remove_group (GBookmarkFile  *bookmark,
  * g_bookmark_file_set_groups:
  * @bookmark: a #GBookmarkFile
  * @uri: an item's URI
- * @groups: an array of group names, or %NULL to remove all groups
+ * @groups: (allow-none): an array of group names, or %NULL to remove all groups
  * @length: number of group name values in @groups
  *
  * Sets a list of group names for the item with URI @uri.  Each previously
@@ -2922,7 +2922,7 @@ g_bookmark_file_set_groups (GBookmarkFile  *bookmark,
  * g_bookmark_file_get_groups:
  * @bookmark: a #GBookmarkFile
  * @uri: a valid URI
- * @length: return location for the length of the returned string, or %NULL
+ * @length: (allow-none): return location for the length of the returned string, or %NULL
  * @error: return location for a #GError, or %NULL
  *
  * Retrieves the list of group names of the bookmark for @uri.
@@ -2994,9 +2994,9 @@ g_bookmark_file_get_groups (GBookmarkFile  *bookmark,
  * g_bookmark_file_add_application:
  * @bookmark: a #GBookmarkFile
  * @uri: a valid URI
- * @name: the name of the application registering the bookmark
+ * @name: (allow-none): the name of the application registering the bookmark
  *   or %NULL
- * @exec: command line to be used to launch the bookmark or %NULL
+ * @exec: (allow-none): command line to be used to launch the bookmark or %NULL
  *
  * Adds the application with @name and @exec to the list of
  * applications that have registered a bookmark for @uri into
@@ -3344,9 +3344,9 @@ expand_exec_line (const gchar *exec_fmt,
  * @bookmark: a #GBookmarkFile
  * @uri: a valid URI
  * @name: an application's name
- * @exec: location for the command line of the application, or %NULL
- * @count: return location for the registration count, or %NULL
- * @stamp: return location for the last registration time, or %NULL
+ * @exec: (allow-none): location for the command line of the application, or %NULL
+ * @count: (allow-none): return location for the registration count, or %NULL
+ * @stamp: (allow-none): return location for the last registration time, or %NULL
  * @error: return location for a #GError, or %NULL
  *
  * Gets the registration informations of @app_name for the bookmark for
@@ -3444,7 +3444,7 @@ g_bookmark_file_get_app_info (GBookmarkFile  *bookmark,
  * g_bookmark_file_get_applications:
  * @bookmark: a #GBookmarkFile
  * @uri: a valid URI
- * @length: return location of the length of the returned list, or %NULL
+ * @length: (allow-none): return location of the length of the returned list, or %NULL
  * @error: return location for a #GError, or %NULL
  *
  * Retrieves the names of the applications that have registered the
@@ -3536,7 +3536,7 @@ g_bookmark_file_get_size (GBookmarkFile *bookmark)
  * g_bookmark_file_move_item:
  * @bookmark: a #GBookmarkFile
  * @old_uri: a valid URI
- * @new_uri: a valid URI, or %NULL
+ * @new_uri: (allow-none): a valid URI, or %NULL
  * @error: return location for a #GError or %NULL
  *
  * Changes the URI of a bookmark item from @old_uri to @new_uri.  Any
@@ -3615,7 +3615,7 @@ g_bookmark_file_move_item (GBookmarkFile  *bookmark,
  * g_bookmark_file_set_icon:
  * @bookmark: a #GBookmarkFile
  * @uri: a valid URI
- * @href: the URI of the icon for the bookmark, or %NULL
+ * @href: (allow-none): the URI of the icon for the bookmark, or %NULL
  * @mime_type: the MIME type of the icon for the bookmark
  *
  * Sets the icon for the bookmark for @uri. If @href is %NULL, unsets
@@ -3664,8 +3664,8 @@ g_bookmark_file_set_icon (GBookmarkFile *bookmark,
  * g_bookmark_file_get_icon:
  * @bookmark: a #GBookmarkFile
  * @uri: a valid URI
- * @href: return location for the icon's location or %NULL
- * @mime_type: return location for the icon's MIME type or %NULL
+ * @href: (allow-none): return location for the icon's location or %NULL
+ * @mime_type: (allow-none): return location for the icon's MIME type or %NULL
  * @error: return location for a #GError or %NULL
  *
  * Gets the icon of the bookmark for @uri.
diff --git a/glib/gconvert.c b/glib/gconvert.c
index 3b2d396f8..e18f3c1d4 100644
--- a/glib/gconvert.c
+++ b/glib/gconvert.c
@@ -1838,7 +1838,7 @@ hostname_validate (const char *hostname)
 /**
  * g_filename_from_uri:
  * @uri: a uri describing a filename (escaped, encoded in ASCII).
- * @hostname: Location to store hostname for the URI, or %NULL.
+ * @hostname: (allow-none): Location to store hostname for the URI, or %NULL.
  *            If there is no hostname in the URI, %NULL will be
  *            stored in this location.
  * @error: location to store the error occurring, or %NULL to ignore
diff --git a/glib/gdataset.c b/glib/gdataset.c
index 263ae18f1..80f5094b9 100644
--- a/glib/gdataset.c
+++ b/glib/gdataset.c
@@ -598,7 +598,7 @@ g_dataset_id_set_data_full (gconstpointer  dataset_location,
  * g_datalist_id_set_data_full:
  * @datalist: a datalist.
  * @key_id: the #GQuark to identify the data element.
- * @data: the data element or %NULL to remove any previous element
+ * @data: (allow-none): the data element or %NULL to remove any previous element
  *        corresponding to @key_id.
  * @destroy_func: the function to call when the data element is
  *                removed. This function will be called with the data
@@ -615,7 +615,7 @@ g_dataset_id_set_data_full (gconstpointer  dataset_location,
  * g_datalist_set_data_full:
  * @dl: a datalist.
  * @k: the string to identify the data element.
- * @d: the data element, or %NULL to remove any previous element
+ * @d: (allow-none): the data element, or %NULL to remove any previous element
  *     corresponding to @k.
  * @f: the function to call when the data element is removed. This
  *     function will be called with the data element and can be used to
@@ -629,7 +629,7 @@ g_dataset_id_set_data_full (gconstpointer  dataset_location,
  * g_datalist_id_set_data:
  * @dl: a datalist.
  * @q: the #GQuark to identify the data element.
- * @d: the data element, or %NULL to remove any previous element
+ * @d: (allow-none): the data element, or %NULL to remove any previous element
  *     corresponding to @q.
  *
  * Sets the data corresponding to the given #GQuark id. Any previous
@@ -640,7 +640,7 @@ g_dataset_id_set_data_full (gconstpointer  dataset_location,
  * g_datalist_set_data:
  * @dl: a datalist.
  * @k: the string to identify the data element.
- * @d: the data element, or %NULL to remove any previous element
+ * @d: (allow-none): the data element, or %NULL to remove any previous element
  *     corresponding to @k.
  *
  * Sets the data element corresponding to the given string identifier.
diff --git a/glib/gdatetime.c b/glib/gdatetime.c
index 69e806ecb..7f78b8498 100644
--- a/glib/gdatetime.c
+++ b/glib/gdatetime.c
@@ -1449,9 +1449,9 @@ g_date_time_equal (gconstpointer dt1,
 /**
  * g_date_time_get_ymd:
  * @datetime: a #GDateTime.
- * @year: (out): the return location for the gregorian year, or %NULL.
- * @month: (out): the return location for the month of the year, or %NULL.
- * @day: (out): the return location for the day of the month, or %NULL.
+ * @year: (out) (allow-none): the return location for the gregorian year, or %NULL.
+ * @month: (out) (allow-none): the return location for the month of the year, or %NULL.
+ * @day: (out) (allow-none): the return location for the day of the month, or %NULL.
  *
  * Retrieves the Gregorian day, month, and year of a given #GDateTime.
  *
diff --git a/glib/gerror.c b/glib/gerror.c
index 6cc3cfb5d..e6ce3c072 100644
--- a/glib/gerror.c
+++ b/glib/gerror.c
@@ -507,7 +507,7 @@ g_error_copy (const GError *error)
 
 /**
  * g_error_matches:
- * @error: a #GError or %NULL
+ * @error: (allow-none): a #GError or %NULL
  * @domain: an error domain
  * @code: an error code
  *
@@ -533,7 +533,7 @@ g_error_matches (const GError *error,
 
 /**
  * g_set_error:
- * @err: a return location for a #GError, or %NULL
+ * @err: (allow-none): a return location for a #GError, or %NULL
  * @domain: error domain
  * @code: error code
  * @format: printf()-style format
@@ -568,7 +568,7 @@ g_set_error (GError      **err,
 
 /**
  * g_set_error_literal:
- * @err: a return location for a #GError, or %NULL
+ * @err: (allow-none): a return location for a #GError, or %NULL
  * @domain: error domain
  * @code: error code
  * @message: error message
@@ -662,7 +662,7 @@ g_error_add_prefix (gchar       **string,
 
 /**
  * g_prefix_error:
- * @err: a return location for a #GError, or %NULL
+ * @err: (allow-none): a return location for a #GError, or %NULL
  * @format: printf()-style format string
  * @...: arguments to @format
  *
diff --git a/glib/ggettext.c b/glib/ggettext.c
index 41b8abcbe..ff1bb6b13 100644
--- a/glib/ggettext.c
+++ b/glib/ggettext.c
@@ -184,7 +184,7 @@ g_strip_context (const gchar *msgid,
 
 /**
  * g_dpgettext:
- * @domain: the translation domain to use, or %NULL to use
+ * @domain: (allow-none): the translation domain to use, or %NULL to use
  *   the domain set with textdomain()
  * @msgctxtid: a combined message context and message id, separated
  *   by a \004 character
@@ -248,7 +248,7 @@ g_dpgettext (const gchar *domain,
  */
 /**
  * g_dpgettext2:
- * @domain: the translation domain to use, or %NULL to use
+ * @domain: (allow-none): the translation domain to use, or %NULL to use
  *   the domain set with textdomain()
  * @context: the message context
  * @msgid: the message
@@ -350,7 +350,7 @@ _g_dgettext_should_translate (void)
 
 /**
  * g_dgettext:
- * @domain: the translation domain to use, or %NULL to use
+ * @domain: (allow-none): the translation domain to use, or %NULL to use
  *   the domain set with textdomain()
  * @msgid: message to translate
  *
@@ -428,7 +428,7 @@ g_dcgettext (const gchar *domain,
 
 /**
  * g_dngettext:
- * @domain: the translation domain to use, or %NULL to use
+ * @domain: (allow-none): the translation domain to use, or %NULL to use
  *   the domain set with textdomain()
  * @msgid: message to translate
  * @msgid_plural: plural form of the message
diff --git a/glib/ghash.c b/glib/ghash.c
index e204a40ad..3fc5b5a13 100644
--- a/glib/ghash.c
+++ b/glib/ghash.c
@@ -664,10 +664,10 @@ g_hash_table_new (GHashFunc  hash_func,
  * g_hash_table_new_full:
  * @hash_func: a function to create a hash value from a key
  * @key_equal_func: a function to check two keys for equality
- * @key_destroy_func: a function to free the memory allocated for the key
+ * @key_destroy_func: (allow-none): a function to free the memory allocated for the key
  *     used when removing the entry from the #GHashTable, or %NULL
  *     if you don't want to supply such a function.
- * @value_destroy_func: a function to free the memory allocated for the
+ * @value_destroy_func: (allow-none): a function to free the memory allocated for the
  *     value used when removing the entry from the #GHashTable, or %NULL
  *     if you don't want to supply such a function.
  *
@@ -745,8 +745,8 @@ g_hash_table_iter_init (GHashTableIter *iter,
 /**
  * g_hash_table_iter_next:
  * @iter: an initialized #GHashTableIter
- * @key: a location to store the key, or %NULL
- * @value: a location to store the value, or %NULL
+ * @key: (allow-none): a location to store the key, or %NULL
+ * @value: (allow-none): a location to store the value, or %NULL
  *
  * Advances @iter and retrieves the key and/or value that are now
  * pointed to as a result of this advancement. If %FALSE is returned,
@@ -855,7 +855,7 @@ g_hash_table_iter_remove (GHashTableIter *iter)
  * @hash_table: our #GHashTable
  * @node_index: pointer to node to insert/replace
  * @key_hash: key hash
- * @key: key to replace with, or %NULL
+ * @key: (allow-none): key to replace with, or %NULL
  * @value: value to replace with
  * @keep_new_key: whether to replace the key in the node with @key
  * @reusing_key: whether @key was taken out of the existing node
diff --git a/glib/giochannel.c b/glib/giochannel.c
index f294701fe..ee9eea2e8 100644
--- a/glib/giochannel.c
+++ b/glib/giochannel.c
@@ -1653,8 +1653,8 @@ reencode:
  *              line terminator. This data should be freed with g_free()
  *              when no longer needed. This is a nul-terminated string. 
  *              If a @length of zero is returned, this will be %NULL instead.
- * @length: location to store length of the read data, or %NULL
- * @terminator_pos: location to store position of line terminator, or %NULL
+ * @length: (allow-none): location to store length of the read data, or %NULL
+ * @terminator_pos: (allow-none): location to store position of line terminator, or %NULL
  * @error: A location to return an error of type #GConvertError
  *         or #GIOChannelError
  *
@@ -1704,7 +1704,7 @@ g_io_channel_read_line (GIOChannel  *channel,
  * @buffer: a #GString into which the line will be written.
  *          If @buffer already contains data, the old data will
  *          be overwritten.
- * @terminator_pos: location to store position of line terminator, or %NULL
+ * @terminator_pos: (allow-none): location to store position of line terminator, or %NULL
  * @error: a location to store an error of type #GConvertError
  *         or #GIOChannelError
  *
diff --git a/glib/gkeyfile.c b/glib/gkeyfile.c
index 62ad387e5..949c8b23d 100644
--- a/glib/gkeyfile.c
+++ b/glib/gkeyfile.c
@@ -920,7 +920,7 @@ g_key_file_load_from_data (GKeyFile       *key_file,
  * @key_file: an empty #GKeyFile struct
  * @file: (type filename): a relative path to a filename to open and parse
  * @search_dirs: (array zero-terminated=1) (element-type filename): %NULL-terminated array of directories to search
- * @full_path: (out) (type filename): return location for a string containing the full path
+ * @full_path: (out) (type filename) (allow-none): return location for a string containing the full path
  *   of the file, or %NULL
  * @flags: flags from #GKeyFileFlags
  * @error: return location for a #GError, or %NULL
@@ -993,7 +993,7 @@ g_key_file_load_from_dirs (GKeyFile       *key_file,
  * g_key_file_load_from_data_dirs:
  * @key_file: an empty #GKeyFile struct
  * @file: (type filename): a relative path to a filename to open and parse
- * @full_path: (out) (type filename): return location for a string containing the full path
+ * @full_path: (out) (type filename) (allow-none): return location for a string containing the full path
  *   of the file, or %NULL
  * @flags: flags from #GKeyFileFlags 
  * @error: return location for a #GError, or %NULL
@@ -1504,7 +1504,7 @@ g_key_file_to_data (GKeyFile  *key_file,
  * g_key_file_get_keys:
  * @key_file: a #GKeyFile
  * @group_name: a group name
- * @length: (out): return location for the number of keys returned, or %NULL
+ * @length: (out) (allow-none): return location for the number of keys returned, or %NULL
  * @error: return location for a #GError, or %NULL
  *
  * Returns all keys for the group name @group_name.  The array of
@@ -3439,7 +3439,7 @@ g_key_file_get_top_comment (GKeyFile  *key_file,
 /**
  * g_key_file_get_comment:
  * @key_file: a #GKeyFile
- * @group_name: a group name, or %NULL
+ * @group_name: (allow-none): a group name, or %NULL
  * @key: a key
  * @error: return location for a #GError
  *
diff --git a/glib/gmain.c b/glib/gmain.c
index fd901e907..68839b590 100644
--- a/glib/gmain.c
+++ b/glib/gmain.c
@@ -618,7 +618,7 @@ static GPrivate thread_context_stack = G_PRIVATE_INIT (free_context_stack);
 
 /**
  * g_main_context_push_thread_default:
- * @context: a #GMainContext, or %NULL for the global default context
+ * @context: (allow-none): a #GMainContext, or %NULL for the global default context
  *
  * Acquires @context and sets it as the thread-default context for the
  * current thread. This will cause certain asynchronous operations
@@ -677,7 +677,7 @@ g_main_context_push_thread_default (GMainContext *context)
 
 /**
  * g_main_context_pop_thread_default:
- * @context: a #GMainContext object, or %NULL
+ * @context: (allow-none): a #GMainContext object, or %NULL
  *
  * Pops @context off the thread-default context stack (verifying that
  * it was on the top of the stack).
@@ -1049,7 +1049,7 @@ g_source_get_id (GSource *source)
  * Gets the #GMainContext with which the source is associated.
  * Calling this function on a destroyed source is an error.
  * 
- * Return value: (transfer none): the #GMainContext with which the
+ * Return value: (transfer none) (allow-none): the #GMainContext with which the
  *               source is associated, or %NULL if the context has not
  *               yet been added to a source.
  **/
@@ -1313,7 +1313,7 @@ static GSourceCallbackFuncs g_source_callback_funcs = {
  * @source: the source
  * @func: a callback function
  * @data: the data to pass to callback function
- * @notify: a function to call when @data is no longer in use, or %NULL.
+ * @notify: (allow-none): a function to call when @data is no longer in use, or %NULL.
  * 
  * Sets the callback function for a source. The callback for a source is
  * called from the source's dispatch function.
@@ -1699,7 +1699,7 @@ g_source_unref (GSource *source)
 
 /**
  * g_main_context_find_source_by_id:
- * @context: a #GMainContext (if %NULL, the default context will be used)
+ * @context: (allow-none): a #GMainContext (if %NULL, the default context will be used)
  * @source_id: the source ID, as returned by g_source_get_id(). 
  * 
  * Finds a #GSource given a pair of context and ID.
@@ -1735,7 +1735,7 @@ g_main_context_find_source_by_id (GMainContext *context,
 
 /**
  * g_main_context_find_source_by_funcs_user_data:
- * @context: a #GMainContext (if %NULL, the default context will be used).
+ * @context: (allow-none): a #GMainContext (if %NULL, the default context will be used).
  * @funcs: the @source_funcs passed to g_source_new().
  * @user_data: the user data from the callback.
  * 
@@ -3131,7 +3131,7 @@ g_main_context_iterate (GMainContext *context,
 
 /**
  * g_main_context_pending:
- * @context: a #GMainContext (if %NULL, the default context will be used)
+ * @context: (allow-none): a #GMainContext (if %NULL, the default context will be used)
  *
  * Checks if any sources have pending events for the given context.
  * 
@@ -3154,7 +3154,7 @@ g_main_context_pending (GMainContext *context)
 
 /**
  * g_main_context_iteration:
- * @context: a #GMainContext (if %NULL, the default context will be used) 
+ * @context: (allow-none): a #GMainContext (if %NULL, the default context will be used) 
  * @may_block: whether the call may block.
  * 
  * Runs a single iteration for the given main loop. This involves
@@ -3474,7 +3474,7 @@ g_main_context_poll (GMainContext *context,
 
 /**
  * g_main_context_add_poll:
- * @context: a #GMainContext (or %NULL for the default context)
+ * @context: (allow-none): a #GMainContext (or %NULL for the default context)
  * @fd: a #GPollFD structure holding information about a file
  *      descriptor to watch.
  * @priority: the priority for this file descriptor which should be
@@ -3934,7 +3934,7 @@ g_timeout_source_new_seconds (guint interval)
  *             (1/1000ths of a second)
  * @function: function to call
  * @data:     data to pass to @function
- * @notify:   function to call when the timeout is removed, or %NULL
+ * @notify: (allow-none): function to call when the timeout is removed, or %NULL
  * 
  * Sets a function to be called at regular intervals, with the given
  * priority.  The function is called repeatedly until it returns
@@ -4032,7 +4032,7 @@ g_timeout_add (guint32        interval,
  * @interval: the time between calls to the function, in seconds
  * @function: function to call
  * @data:     data to pass to @function
- * @notify:   function to call when the timeout is removed, or %NULL
+ * @notify: (allow-none): function to call when the timeout is removed, or %NULL
  *
  * Sets a function to be called at regular intervals, with @priority.
  * The function is called repeatedly until it returns %FALSE, at which
@@ -4513,7 +4513,7 @@ g_child_watch_source_new (GPid pid)
  * Windows a handle for a process (which doesn't have to be a child).
  * @function: function to call
  * @data:     data to pass to @function
- * @notify:   function to call when the idle is removed, or %NULL
+ * @notify: (allow-none): function to call when the idle is removed, or %NULL
  * 
  * Sets a function to be called when the child indicated by @pid 
  * exits, at the priority @priority.
@@ -4664,7 +4664,7 @@ g_idle_source_new (void)
  *            range between #G_PRIORITY_DEFAULT_IDLE and #G_PRIORITY_HIGH_IDLE.
  * @function: function to call
  * @data:     data to pass to @function
- * @notify:   function to call when the idle is removed, or %NULL
+ * @notify: (allow-none): function to call when the idle is removed, or %NULL
  * 
  * Adds a function to be called whenever there are no higher priority
  * events pending.  If the function returns %FALSE it is automatically
@@ -4784,7 +4784,7 @@ g_main_context_invoke (GMainContext *context,
  * @priority: the priority at which to run @function
  * @function: function to call
  * @data: data to pass to @function
- * @notify: a function to call when @data is no longer in use, or %NULL.
+ * @notify: (allow-none): a function to call when @data is no longer in use, or %NULL.
  *
  * Invokes a function in such a way that @context is owned during the
  * invocation of @function.
diff --git a/glib/gmem.c b/glib/gmem.c
index 488bff869..bdb788c6c 100644
--- a/glib/gmem.c
+++ b/glib/gmem.c
@@ -305,7 +305,7 @@ g_try_malloc0 (gsize n_bytes)
 
 /**
  * g_try_realloc:
- * @mem: previously-allocated memory, or %NULL.
+ * @mem: (allow-none): previously-allocated memory, or %NULL.
  * @n_bytes: number of bytes to allocate.
  * 
  * Attempts to realloc @mem to a new size, @n_bytes, and returns %NULL
@@ -455,7 +455,7 @@ g_try_malloc0_n (gsize n_blocks,
 
 /**
  * g_try_realloc_n:
- * @mem: previously-allocated memory, or %NULL.
+ * @mem: (allow-none): previously-allocated memory, or %NULL.
  * @n_blocks: the number of blocks to allocate
  * @n_block_bytes: the size of each block in bytes
  * 
diff --git a/glib/gmessages.c b/glib/gmessages.c
index 4230f083e..f32d51c35 100644
--- a/glib/gmessages.c
+++ b/glib/gmessages.c
@@ -448,7 +448,7 @@ g_log_set_fatal_mask (const gchar   *log_domain,
 
 /**
  * g_log_set_handler:
- * @log_domain: the log domain, or %NULL for the default ""
+ * @log_domain: (allow-none): the log domain, or %NULL for the default ""
  *     application domain
  * @log_levels: the log levels to apply the log handler for.
  *     To handle fatal and recursive messages as well, combine
diff --git a/glib/goption.c b/glib/goption.c
index c1c520d87..5cfff57ff 100644
--- a/glib/goption.c
+++ b/glib/goption.c
@@ -559,7 +559,7 @@ g_option_context_get_main_group (GOptionContext *context)
  * g_option_context_add_main_entries:
  * @context: a #GOptionContext
  * @entries: a %NULL-terminated array of #GOptionEntry<!-- -->s
- * @translation_domain: a translation domain to use for translating
+ * @translation_domain: (allow-none): a translation domain to use for translating
  *    the <option>--help</option> output for the options in @entries
  *    with gettext(), or %NULL
  *
@@ -716,7 +716,7 @@ context_has_h_entry (GOptionContext *context)
  * g_option_context_get_help:
  * @context: a #GOptionContext
  * @main_help: if %TRUE, only include the main group
- * @group: the #GOptionGroup to create help for, or %NULL
+ * @group: (allow-none): the #GOptionGroup to create help for, or %NULL
  *
  * Returns a formatted, translated help text for the given context.
  * To obtain the text produced by <option>--help</option>, call
@@ -2087,9 +2087,9 @@ g_option_context_parse (GOptionContext   *context,
  * @help_description: a description for the <option>--help-</option>@name option.
  *   This string is translated using the translation domain or translation function
  *   of the group
- * @user_data: user data that will be passed to the pre- and post-parse hooks,
+ * @user_data: (allow-none): user data that will be passed to the pre- and post-parse hooks,
  *   the error hook and to callbacks of %G_OPTION_ARG_CALLBACK options, or %NULL
- * @destroy: a function that will be called to free @user_data, or %NULL
+ * @destroy: (allow-none): a function that will be called to free @user_data, or %NULL
  *
  * Creates a new #GOptionGroup.
  *
@@ -2208,8 +2208,8 @@ g_option_group_add_entries (GOptionGroup       *group,
 /**
  * g_option_group_set_parse_hooks:
  * @group: a #GOptionGroup
- * @pre_parse_func: a function to call before parsing, or %NULL
- * @post_parse_func: a function to call after parsing, or %NULL
+ * @pre_parse_func: (allow-none): a function to call before parsing, or %NULL
+ * @post_parse_func: (allow-none): a function to call after parsing, or %NULL
  *
  * Associates two functions with @group which will be called
  * from g_option_context_parse() before the first option is parsed
@@ -2258,9 +2258,9 @@ g_option_group_set_error_hook (GOptionGroup     *group,
 /**
  * g_option_group_set_translate_func:
  * @group: a #GOptionGroup
- * @func: the #GTranslateFunc, or %NULL
- * @data: user data to pass to @func, or %NULL
- * @destroy_notify: a function which gets called to free @data, or %NULL
+ * @func: (allow-none): the #GTranslateFunc, or %NULL
+ * @data: (allow-none): user data to pass to @func, or %NULL
+ * @destroy_notify: (allow-none): a function which gets called to free @data, or %NULL
  *
  * Sets the function which is used to translate user-visible
  * strings, for <option>--help</option> output. Different
@@ -2320,9 +2320,9 @@ g_option_group_set_translation_domain (GOptionGroup *group,
 /**
  * g_option_context_set_translate_func:
  * @context: a #GOptionContext
- * @func: the #GTranslateFunc, or %NULL
- * @data: user data to pass to @func, or %NULL
- * @destroy_notify: a function which gets called to free @data, or %NULL
+ * @func: (allow-none): the #GTranslateFunc, or %NULL
+ * @data: (allow-none): user data to pass to @func, or %NULL
+ * @destroy_notify: (allow-none): a function which gets called to free @data, or %NULL
  *
  * Sets the function which is used to translate the contexts
  * user-visible strings, for <option>--help</option> output.
@@ -2379,7 +2379,7 @@ g_option_context_set_translation_domain (GOptionContext *context,
 /**
  * g_option_context_set_summary:
  * @context: a #GOptionContext
- * @summary: a string to be shown in <option>--help</option> output
+ * @summary: (allow-none): a string to be shown in <option>--help</option> output
  *  before the list of options, or %NULL
  *
  * Adds a string to be displayed in <option>--help</option> output
@@ -2424,7 +2424,7 @@ g_option_context_get_summary (GOptionContext *context)
 /**
  * g_option_context_set_description:
  * @context: a #GOptionContext
- * @description: a string to be shown in <option>--help</option> output
+ * @description: (allow-none): a string to be shown in <option>--help</option> output
  *   after the list of options, or %NULL
  *
  * Adds a string to be displayed in <option>--help</option> output
diff --git a/glib/gpattern.c b/glib/gpattern.c
index 7770d9ca2..bc0cc714c 100644
--- a/glib/gpattern.c
+++ b/glib/gpattern.c
@@ -167,7 +167,7 @@ g_pattern_ph_match (const gchar *match_pattern,
  * @string_length: the length of @string (in bytes, i.e. strlen(),
  *                 <emphasis>not</emphasis> g_utf8_strlen())
  * @string: the UTF-8 encoded string to match
- * @string_reversed: the reverse of @string or %NULL
+ * @string_reversed: (allow-none): the reverse of @string or %NULL
  * @Returns: %TRUE if @string matches @pspec
  *
  * Matches a string against a compiled pattern. Passing the correct
diff --git a/glib/gregex.c b/glib/gregex.c
index ffffda7ee..bf82bd14d 100644
--- a/glib/gregex.c
+++ b/glib/gregex.c
@@ -779,7 +779,7 @@ g_match_info_is_partial_match (const GMatchInfo *match_info)
 
 /**
  * g_match_info_expand_references:
- * @match_info: a #GMatchInfo or %NULL
+ * @match_info: (allow-none): a #GMatchInfo or %NULL
  * @string_to_expand: the string to expand
  * @error: location to store the error occurring, or %NULL to ignore errors
  *
diff --git a/glib/gsequence.c b/glib/gsequence.c
index 165fb38d7..ee3da34e0 100644
--- a/glib/gsequence.c
+++ b/glib/gsequence.c
@@ -239,7 +239,7 @@ iter_compare (GSequenceIter *node1,
 
 /**
  * g_sequence_new:
- * @data_destroy: a #GDestroyNotify function, or %NULL
+ * @data_destroy: (allow-none): a #GDestroyNotify function, or %NULL
  *
  * Creates a new GSequence. The @data_destroy function, if non-%NULL will
  * be called on all items when the sequence is destroyed and on items that
diff --git a/glib/gstdio.c b/glib/gstdio.c
index 1908918cb..6d763e1f6 100644
--- a/glib/gstdio.c
+++ b/glib/gstdio.c
@@ -737,7 +737,7 @@ g_fopen (const gchar *filename,
  * @filename: a pathname in the GLib file name encoding (UTF-8 on Windows)
  * @mode: a string describing the mode in which the file should be 
  *   opened
- * @stream: an existing stream which will be reused, or %NULL
+ * @stream: (allow-none): an existing stream which will be reused, or %NULL
  *
  * A wrapper for the POSIX freopen() function. The freopen() function
  * opens a file and associates it with an existing stream.
diff --git a/glib/gstrfuncs.c b/glib/gstrfuncs.c
index 19365b2d5..777d12e96 100644
--- a/glib/gstrfuncs.c
+++ b/glib/gstrfuncs.c
@@ -1891,7 +1891,7 @@ g_strncasecmp (const gchar *s1,
 /**
  * g_strdelimit:
  * @string: the string to convert
- * @delimiters: a string containing the current delimiters, or %NULL
+ * @delimiters: (allow-none): a string containing the current delimiters, or %NULL
  *     to use the standard delimiters defined in #G_STR_DELIMITERS
  * @new_delimiter: the new delimiter character
  *
@@ -2441,7 +2441,7 @@ g_strdupv (gchar **str_array)
 
 /**
  * g_strjoinv:
- * @separator: a string to insert between each of the strings, or %NULL
+ * @separator: (allow-none): a string to insert between each of the strings, or %NULL
  * @str_array: a %NULL-terminated array of strings to join
  *
  * Joins a number of strings together to form one long string, with the
@@ -2493,7 +2493,7 @@ g_strjoinv (const gchar  *separator,
 
 /**
  * g_strjoin:
- * @separator: a string to insert between each of the strings, or %NULL
+ * @separator: (allow-none): a string to insert between each of the strings, or %NULL
  * @...: a %NULL-terminated list of strings to join
  *
  * Joins a number of strings together to form one long string, with the
diff --git a/glib/gtestutils.c b/glib/gtestutils.c
index e9d7f84a4..c1644cc8e 100644
--- a/glib/gtestutils.c
+++ b/glib/gtestutils.c
@@ -1954,8 +1954,8 @@ g_assertion_message_error (const char     *domain,
 
 /**
  * g_strcmp0:
- * @str1: a C string or %NULL
- * @str2: another C string or %NULL
+ * @str1: (allow-none): a C string or %NULL
+ * @str2: (allow-none): another C string or %NULL
  *
  * Compares @str1 and @str2 like strcmp(). Handles %NULL 
  * gracefully by sorting it before non-%NULL strings.
diff --git a/glib/gunidecomp.c b/glib/gunidecomp.c
index 8ba24fded..2ee98945e 100644
--- a/glib/gunidecomp.c
+++ b/glib/gunidecomp.c
@@ -685,7 +685,7 @@ g_unichar_compose (gunichar  a,
  * g_unichar_fully_decompose:
  * @ch: a Unicode character.
  * @compat: whether perform canonical or compatibility decomposition
- * @result: location to store decomposed result, or %NULL
+ * @result: (allow-none): location to store decomposed result, or %NULL
  * @result_len: length of @result
  *
  * Computes the canonical or compatibility decomposition of a
diff --git a/glib/gutf8.c b/glib/gutf8.c
index e1e0003dd..19be7598b 100644
--- a/glib/gutf8.c
+++ b/glib/gutf8.c
@@ -696,7 +696,7 @@ g_utf8_get_char_validated (const  gchar *p,
  * @str: a UTF-8 encoded string
  * @len: the maximum length of @str to use, in bytes. If @len < 0,
  *       then the string is nul-terminated.
- * @items_written: location to store the number of characters in the
+ * @items_written: (allow-none): location to store the number of characters in the
  *                 result, or %NULL.
  *
  * Convert a string from UTF-8 to a 32-bit fixed width
@@ -789,12 +789,12 @@ g_utf8_to_ucs4_fast (const gchar *str,
  * @str: a UTF-8 encoded string
  * @len: the maximum length of @str to use, in bytes. If @len < 0,
  *       then the string is nul-terminated.
- * @items_read: location to store number of bytes read, or %NULL.
+ * @items_read: (allow-none): location to store number of bytes read, or %NULL.
  *              If %NULL, then %G_CONVERT_ERROR_PARTIAL_INPUT will be
  *              returned in case @str contains a trailing partial
  *              character. If an error occurs then the index of the
  *              invalid input is stored here.
- * @items_written: location to store number of characters written or %NULL.
+ * @items_written: (allow-none): location to store number of characters written or %NULL.
  *                 The value here stored does not include the trailing 0
  *                 character. 
  * @error: location to store the error occurring, or %NULL to ignore
@@ -873,8 +873,8 @@ g_utf8_to_ucs4 (const gchar *str,
  * @str: a UCS-4 encoded string
  * @len: the maximum length (number of characters) of @str to use. 
  *       If @len < 0, then the string is nul-terminated.
- * @items_read: location to store number of characters read, or %NULL.
- * @items_written: location to store number of bytes written or %NULL.
+ * @items_read: (allow-none): location to store number of characters read, or %NULL.
+ * @items_written: (allow-none): location to store number of bytes written or %NULL.
  *                 The value here stored does not include the trailing 0
  *                 byte. 
  * @error: location to store the error occurring, or %NULL to ignore
@@ -945,12 +945,12 @@ g_ucs4_to_utf8 (const gunichar *str,
  * @str: a UTF-16 encoded string
  * @len: the maximum length (number of <type>gunichar2</type>) of @str to use. 
  *       If @len < 0, then the string is nul-terminated.
- * @items_read: location to store number of words read, or %NULL.
+ * @items_read: (allow-none): location to store number of words read, or %NULL.
  *              If %NULL, then %G_CONVERT_ERROR_PARTIAL_INPUT will be
  *              returned in case @str contains a trailing partial
  *              character. If an error occurs then the index of the
  *              invalid input is stored here.
- * @items_written: location to store number of bytes written, or %NULL.
+ * @items_written: (allow-none): location to store number of bytes written, or %NULL.
  *                 The value stored here does not include the trailing
  *                 0 byte.
  * @error: location to store the error occurring, or %NULL to ignore
@@ -1100,12 +1100,12 @@ g_utf16_to_utf8 (const gunichar2  *str,
  * @str: a UTF-16 encoded string
  * @len: the maximum length (number of <type>gunichar2</type>) of @str to use. 
  *       If @len < 0, then the string is nul-terminated.
- * @items_read: location to store number of words read, or %NULL.
+ * @items_read: (allow-none): location to store number of words read, or %NULL.
  *              If %NULL, then %G_CONVERT_ERROR_PARTIAL_INPUT will be
  *              returned in case @str contains a trailing partial
  *              character. If an error occurs then the index of the
  *              invalid input is stored here.
- * @items_written: location to store number of characters written, or %NULL.
+ * @items_written: (allow-none): location to store number of characters written, or %NULL.
  *                 The value stored here does not include the trailing
  *                 0 character.
  * @error: location to store the error occurring, or %NULL to ignore
@@ -1238,12 +1238,12 @@ g_utf16_to_ucs4 (const gunichar2  *str,
  * @str: a UTF-8 encoded string
  * @len: the maximum length (number of bytes) of @str to use.
  *       If @len < 0, then the string is nul-terminated.
- * @items_read: location to store number of bytes read, or %NULL.
+ * @items_read: (allow-none): location to store number of bytes read, or %NULL.
  *              If %NULL, then %G_CONVERT_ERROR_PARTIAL_INPUT will be
  *              returned in case @str contains a trailing partial
  *              character. If an error occurs then the index of the
  *              invalid input is stored here.
- * @items_written: location to store number of <type>gunichar2</type> written,
+ * @items_written: (allow-none): location to store number of <type>gunichar2</type> written,
  *                 or %NULL.
  *                 The value stored here does not include the trailing 0.
  * @error: location to store the error occurring, or %NULL to ignore
@@ -1355,10 +1355,10 @@ g_utf8_to_utf16 (const gchar *str,
  * @str: a UCS-4 encoded string
  * @len: the maximum length (number of characters) of @str to use. 
  *       If @len < 0, then the string is nul-terminated.
- * @items_read: location to store number of bytes read, or %NULL.
+ * @items_read: (allow-none): location to store number of bytes read, or %NULL.
  *              If an error occurs then the index of the invalid input
  *              is stored here.
- * @items_written: location to store number of <type>gunichar2</type> 
+ * @items_written: (allow-none): location to store number of <type>gunichar2</type> 
  *                 written, or %NULL. The value stored here does not 
  *                 include the trailing 0.
  * @error: location to store the error occurring, or %NULL to ignore
diff --git a/glib/gvariant-parser.c b/glib/gvariant-parser.c
index c0dc8dac4..0d1b093e4 100644
--- a/glib/gvariant-parser.c
+++ b/glib/gvariant-parser.c
@@ -2306,11 +2306,11 @@ parse (TokenStream  *stream,
 
 /**
  * g_variant_parse:
- * @type: a #GVariantType, or %NULL
+ * @type: (allow-none): a #GVariantType, or %NULL
  * @text: a string containing a GVariant in text form
- * @limit: a pointer to the end of @text, or %NULL
- * @endptr: a location to store the end pointer, or %NULL
- * @error: a pointer to a %NULL #GError pointer, or %NULL
+ * @limit: (allow-none): a pointer to the end of @text, or %NULL
+ * @endptr: (allow-none): a location to store the end pointer, or %NULL
+ * @error: (allow-none): a pointer to a %NULL #GError pointer, or %NULL
  * @Returns: a reference to a #GVariant, or %NULL
  *
  * Parses a #GVariant from a text representation.
diff --git a/glib/gvariant-serialiser.c b/glib/gvariant-serialiser.c
index f07251176..d4b668bb8 100644
--- a/glib/gvariant-serialiser.c
+++ b/glib/gvariant-serialiser.c
@@ -89,7 +89,7 @@
 /* < private >
  * GVariantSerialised:
  * @type_info: the #GVariantTypeInfo of this value
- * @data: the serialised data of this value, or %NULL
+ * @data: (allow-none): the serialised data of this value, or %NULL
  * @size: the size of this value
  *
  * A structure representing a GVariant in serialised form.  This
diff --git a/glib/gvarianttype.c b/glib/gvarianttype.c
index a242a3845..5c27fe0f9 100644
--- a/glib/gvarianttype.c
+++ b/glib/gvarianttype.c
@@ -597,7 +597,7 @@ g_variant_type_string_is_valid (const gchar *type_string)
 
 /**
  * g_variant_type_free:
- * @type: a #GVariantType, or %NULL
+ * @type: (allow-none): a #GVariantType, or %NULL
  *
  * Frees a #GVariantType that was allocated with
  * g_variant_type_copy(), g_variant_type_new() or one of the container
diff --git a/glib/gvarianttypeinfo.c b/glib/gvarianttypeinfo.c
index 0c380ce1f..7a76d272f 100644
--- a/glib/gvarianttypeinfo.c
+++ b/glib/gvarianttypeinfo.c
@@ -222,8 +222,8 @@ g_variant_type_info_get_type_string (GVariantTypeInfo *info)
 /* < private >
  * g_variant_type_info_query:
  * @info: a #GVariantTypeInfo
- * @alignment: the location to store the alignment, or %NULL
- * @fixed_size: the location to store the fixed size, or %NULL
+ * @alignment: (allow-none): the location to store the alignment, or %NULL
+ * @fixed_size: (allow-none): the location to store the fixed size, or %NULL
  *
  * Queries @info to determine the alignment requirements and fixed size
  * (if any) of the type.
@@ -306,8 +306,8 @@ g_variant_type_info_element (GVariantTypeInfo *info)
 /* < private >
  * g_variant_type_query_element:
  * @info: a #GVariantTypeInfo for an array or maybe type
- * @alignment: the location to store the alignment, or %NULL
- * @fixed_size: the location to store the fixed size, or %NULL
+ * @alignment: (allow-none): the location to store the alignment, or %NULL
+ * @fixed_size: (allow-none): the location to store the fixed size, or %NULL
  *
  * Returns the alignment requires and fixed size (if any) for the
  * element type of the array.  This call is a convenience wrapper around
diff --git a/glib/gwin32.c b/glib/gwin32.c
index e12fa7a86..97eccd76e 100644
--- a/glib/gwin32.c
+++ b/glib/gwin32.c
@@ -203,7 +203,7 @@ g_win32_error_message (gint error)
 
 /**
  * g_win32_get_package_installation_directory_of_module:
- * @hmodule: The Win32 handle for a DLL loaded into the current process, or %NULL
+ * @hmodule: (allow-none): The Win32 handle for a DLL loaded into the current process, or %NULL
  *
  * This function tries to determine the installation directory of a
  * software package based on the location of a DLL of the software
@@ -322,8 +322,8 @@ get_package_directory_from_module (const gchar *module_name)
 
 /**
  * g_win32_get_package_installation_directory:
- * @package: You should pass %NULL for this.
- * @dll_name: The name of a DLL that a package provides in UTF-8, or %NULL.
+ * @package: (allow-none): You should pass %NULL for this.
+ * @dll_name: (allow-none): The name of a DLL that a package provides in UTF-8, or %NULL.
  *
  * Try to determine the installation directory for a software package.
  *
@@ -428,8 +428,8 @@ g_win32_get_package_installation_directory (const gchar *package,
 
 /**
  * g_win32_get_package_installation_subdirectory:
- * @package: You should pass %NULL for this.
- * @dll_name: The name of a DLL that a package provides, in UTF-8, or %NULL.
+ * @package: (allow-none): You should pass %NULL for this.
+ * @dll_name: (allow-none): The name of a DLL that a package provides, in UTF-8, or %NULL.
  * @subdir: A subdirectory of the package installation directory, also in UTF-8
  *
  * This function is deprecated. Use
diff --git a/gmodule/gmodule.c b/gmodule/gmodule.c
index 22db6d0dd..f166dba98 100644
--- a/gmodule/gmodule.c
+++ b/gmodule/gmodule.c
@@ -681,7 +681,7 @@ g_module_open (const gchar    *file_name,
 
 /**
  * g_module_open:
- * @file_name: the name of the file containing the module, or %NULL
+ * @file_name: (allow-none): the name of the file containing the module, or %NULL
  *     to obtain a #GModule representing the main program itself
  * @flags: the flags used for opening the module. This can be the
  *     logical OR of any of the #GModuleFlags