diff --git a/gio/gcancellable.c b/gio/gcancellable.c
index de6d43495..32605ce02 100644
--- a/gio/gcancellable.c
+++ b/gio/gcancellable.c
@@ -43,7 +43,9 @@ enum {
 
 struct _GCancellablePrivate
 {
-  guint cancelled : 1;
+  /* Atomic so that g_cancellable_is_cancelled does not require holding the mutex. */
+  gboolean cancelled;
+  /* Access to fields below is protected by cancellable_mutex. */
   guint cancelled_running : 1;
   guint cancelled_running_waiting : 1;
 
@@ -269,12 +271,12 @@ g_cancellable_reset (GCancellable *cancellable)
       g_cond_wait (&cancellable_cond, &cancellable_mutex);
     }
 
-  if (priv->cancelled)
+  if (g_atomic_int_get (&priv->cancelled))
     {
       if (priv->wakeup)
         GLIB_PRIVATE_CALL (g_wakeup_acknowledge) (priv->wakeup);
 
-      priv->cancelled = FALSE;
+      g_atomic_int_set (&priv->cancelled, FALSE);
     }
 
   g_mutex_unlock (&cancellable_mutex);
@@ -292,7 +294,7 @@ g_cancellable_reset (GCancellable *cancellable)
 gboolean
 g_cancellable_is_cancelled (GCancellable *cancellable)
 {
-  return cancellable != NULL && cancellable->priv->cancelled;
+  return cancellable != NULL && g_atomic_int_get (&cancellable->priv->cancelled);
 }
 
 /**
@@ -404,7 +406,7 @@ g_cancellable_make_pollfd (GCancellable *cancellable, GPollFD *pollfd)
     {
       cancellable->priv->wakeup = GLIB_PRIVATE_CALL (g_wakeup_new) ();
 
-      if (cancellable->priv->cancelled)
+      if (g_atomic_int_get (&cancellable->priv->cancelled))
         GLIB_PRIVATE_CALL (g_wakeup_signal) (cancellable->priv->wakeup);
     }
 
@@ -440,11 +442,11 @@ g_cancellable_release_fd (GCancellable *cancellable)
     return;
 
   g_return_if_fail (G_IS_CANCELLABLE (cancellable));
-  g_return_if_fail (cancellable->priv->fd_refcount > 0);
 
   priv = cancellable->priv;
 
   g_mutex_lock (&cancellable_mutex);
+  g_assert (priv->fd_refcount > 0);
 
   priv->fd_refcount--;
   if (priv->fd_refcount == 0)
@@ -482,21 +484,20 @@ g_cancellable_cancel (GCancellable *cancellable)
 {
   GCancellablePrivate *priv;
 
-  if (cancellable == NULL ||
-      cancellable->priv->cancelled)
+  if (g_cancellable_is_cancelled (cancellable))
     return;
 
   priv = cancellable->priv;
 
   g_mutex_lock (&cancellable_mutex);
 
-  if (priv->cancelled)
+  if (g_atomic_int_get (&priv->cancelled))
     {
       g_mutex_unlock (&cancellable_mutex);
       return;
     }
 
-  priv->cancelled = TRUE;
+  g_atomic_int_set (&priv->cancelled, TRUE);
   priv->cancelled_running = TRUE;
 
   if (priv->wakeup)
@@ -562,7 +563,7 @@ g_cancellable_connect (GCancellable   *cancellable,
 
   g_mutex_lock (&cancellable_mutex);
 
-  if (cancellable->priv->cancelled)
+  if (g_atomic_int_get (&cancellable->priv->cancelled))
     {
       void (*_callback) (GCancellable *cancellable,
                          gpointer      user_data);
diff --git a/gio/glocalfilemonitor.c b/gio/glocalfilemonitor.c
index 8a4c4ec43..278d9a492 100644
--- a/gio/glocalfilemonitor.c
+++ b/gio/glocalfilemonitor.c
@@ -788,11 +788,11 @@ g_local_file_monitor_start (GLocalFileMonitor *local_monitor,
 #endif
     }
 
+  g_source_attach ((GSource *) source, context);
+
   G_LOCAL_FILE_MONITOR_GET_CLASS (local_monitor)->start (local_monitor,
                                                          source->dirname, source->basename, source->filename,
                                                          source);
-
-  g_source_attach ((GSource *) source, context);
 }
 
 static void
diff --git a/gio/tests/gdbus-test-codegen.c b/gio/tests/gdbus-test-codegen.c
index 8db555781..985cb1095 100644
--- a/gio/tests/gdbus-test-codegen.c
+++ b/gio/tests/gdbus-test-codegen.c
@@ -583,10 +583,8 @@ on_name_acquired (GDBusConnection *connection,
                   gpointer         user_data)
 {
   GMainLoop *loop = user_data;
-
-  g_thread_new ("check-proxies",
-                check_proxies_in_thread,
-                loop);
+  GThread *thread = g_thread_new ("check-proxies", check_proxies_in_thread, loop);
+  g_thread_unref (thread);
 }
 
 static void
diff --git a/glib/gmain.c b/glib/gmain.c
index 83e398cfa..860c39dd1 100644
--- a/glib/gmain.c
+++ b/glib/gmain.c
@@ -309,7 +309,7 @@ struct _GSourceCallback
 struct _GMainLoop
 {
   GMainContext *context;
-  gboolean is_running;
+  gboolean is_running; /* (atomic) */
   volatile gint ref_count;
 };
 
@@ -4087,16 +4087,14 @@ g_main_loop_run (GMainLoop *loop)
       LOCK_CONTEXT (loop->context);
 
       g_atomic_int_inc (&loop->ref_count);
+      g_atomic_int_set (&loop->is_running, TRUE);
 
-      if (!loop->is_running)
-	loop->is_running = TRUE;
-
-      while (loop->is_running && !got_ownership)
+      while (g_atomic_int_get (&loop->is_running) && !got_ownership)
         got_ownership = g_main_context_wait_internal (loop->context,
                                                       &loop->context->cond,
                                                       &loop->context->mutex);
       
-      if (!loop->is_running)
+      if (!g_atomic_int_get (&loop->is_running))
 	{
 	  UNLOCK_CONTEXT (loop->context);
 	  if (got_ownership)
@@ -4118,8 +4116,8 @@ g_main_loop_run (GMainLoop *loop)
     }
 
   g_atomic_int_inc (&loop->ref_count);
-  loop->is_running = TRUE;
-  while (loop->is_running)
+  g_atomic_int_set (&loop->is_running, TRUE);
+  while (g_atomic_int_get (&loop->is_running))
     g_main_context_iterate (loop->context, TRUE, TRUE, self);
 
   UNLOCK_CONTEXT (loop->context);
@@ -4146,7 +4144,7 @@ g_main_loop_quit (GMainLoop *loop)
   g_return_if_fail (g_atomic_int_get (&loop->ref_count) > 0);
 
   LOCK_CONTEXT (loop->context);
-  loop->is_running = FALSE;
+  g_atomic_int_set (&loop->is_running, FALSE);
   g_wakeup_signal (loop->context->wakeup);
 
   g_cond_broadcast (&loop->context->cond);
@@ -4170,7 +4168,7 @@ g_main_loop_is_running (GMainLoop *loop)
   g_return_val_if_fail (loop != NULL, FALSE);
   g_return_val_if_fail (g_atomic_int_get (&loop->ref_count) > 0, FALSE);
 
-  return loop->is_running;
+  return g_atomic_int_get (&loop->is_running);
 }
 
 /**
diff --git a/gobject/gobject.c b/gobject/gobject.c
index de61a0481..22c2cb39e 100644
--- a/gobject/gobject.c
+++ b/gobject/gobject.c
@@ -263,7 +263,6 @@ g_object_notify_queue_thaw (GObject            *object,
   GSList *slist;
   guint n_pspecs = 0;
 
-  g_return_if_fail (nqueue->freeze_count > 0);
   g_return_if_fail (g_atomic_int_get(&object->ref_count) > 0);
 
   G_LOCK(notify_lock);
@@ -1101,7 +1100,7 @@ void
 g_object_run_dispose (GObject *object)
 {
   g_return_if_fail (G_IS_OBJECT (object));
-  g_return_if_fail (object->ref_count > 0);
+  g_return_if_fail (g_atomic_int_get (&object->ref_count) > 0);
 
   g_object_ref (object);
   TRACE (GOBJECT_OBJECT_DISPOSE(object,G_TYPE_FROM_INSTANCE(object), 0));
@@ -2819,7 +2818,7 @@ g_object_weak_ref (GObject    *object,
   
   g_return_if_fail (G_IS_OBJECT (object));
   g_return_if_fail (notify != NULL);
-  g_return_if_fail (object->ref_count >= 1);
+  g_return_if_fail (g_atomic_int_get (&object->ref_count) >= 1);
 
   G_LOCK (weak_refs_mutex);
   wstack = g_datalist_id_remove_no_notify (&object->qdata, quark_weak_refs);
@@ -3001,7 +3000,7 @@ gpointer
   GObject *object = _object;
   gboolean was_floating;
   g_return_val_if_fail (G_IS_OBJECT (object), object);
-  g_return_val_if_fail (object->ref_count >= 1, object);
+  g_return_val_if_fail (g_atomic_int_get (&object->ref_count) >= 1, object);
   g_object_ref (object);
   was_floating = floating_flag_handler (object, -1);
   if (was_floating)
@@ -3024,7 +3023,7 @@ void
 g_object_force_floating (GObject *object)
 {
   g_return_if_fail (G_IS_OBJECT (object));
-  g_return_if_fail (object->ref_count >= 1);
+  g_return_if_fail (g_atomic_int_get (&object->ref_count) >= 1);
 
   floating_flag_handler (object, +1);
 }
@@ -3105,7 +3104,7 @@ g_object_add_toggle_ref (GObject       *object,
   
   g_return_if_fail (G_IS_OBJECT (object));
   g_return_if_fail (notify != NULL);
-  g_return_if_fail (object->ref_count >= 1);
+  g_return_if_fail (g_atomic_int_get (&object->ref_count) >= 1);
 
   g_object_ref (object);
 
@@ -4139,7 +4138,7 @@ g_object_watch_closure (GObject  *object,
   g_return_if_fail (closure != NULL);
   g_return_if_fail (closure->is_invalid == FALSE);
   g_return_if_fail (closure->in_marshal == FALSE);
-  g_return_if_fail (object->ref_count > 0);	/* this doesn't work on finalizing objects */
+  g_return_if_fail (g_atomic_int_get (&object->ref_count) > 0);	/* this doesn't work on finalizing objects */
   
   g_closure_add_invalidate_notifier (closure, object, object_remove_closure);
   g_closure_add_marshal_guards (closure,
@@ -4185,7 +4184,7 @@ g_closure_new_object (guint    sizeof_closure,
   GClosure *closure;
 
   g_return_val_if_fail (G_IS_OBJECT (object), NULL);
-  g_return_val_if_fail (object->ref_count > 0, NULL);     /* this doesn't work on finalizing objects */
+  g_return_val_if_fail (g_atomic_int_get (&object->ref_count) > 0, NULL);     /* this doesn't work on finalizing objects */
 
   closure = g_closure_new_simple (sizeof_closure, object);
   g_object_watch_closure (object, closure);
@@ -4213,7 +4212,7 @@ g_cclosure_new_object (GCallback callback_func,
   GClosure *closure;
 
   g_return_val_if_fail (G_IS_OBJECT (object), NULL);
-  g_return_val_if_fail (object->ref_count > 0, NULL);     /* this doesn't work on finalizing objects */
+  g_return_val_if_fail (g_atomic_int_get (&object->ref_count) > 0, NULL);     /* this doesn't work on finalizing objects */
   g_return_val_if_fail (callback_func != NULL, NULL);
 
   closure = g_cclosure_new (callback_func, object, NULL);
@@ -4242,7 +4241,7 @@ g_cclosure_new_object_swap (GCallback callback_func,
   GClosure *closure;
 
   g_return_val_if_fail (G_IS_OBJECT (object), NULL);
-  g_return_val_if_fail (object->ref_count > 0, NULL);     /* this doesn't work on finalizing objects */
+  g_return_val_if_fail (g_atomic_int_get (&object->ref_count) > 0, NULL);     /* this doesn't work on finalizing objects */
   g_return_val_if_fail (callback_func != NULL, NULL);
 
   closure = g_cclosure_new_swap (callback_func, object, NULL);
diff --git a/gobject/gparam.c b/gobject/gparam.c
index 79ee834d5..6f33f027b 100644
--- a/gobject/gparam.c
+++ b/gobject/gparam.c
@@ -1561,8 +1561,7 @@ g_param_spec_get_default_value (GParamSpec *pspec)
       g_param_value_set_default (pspec, &default_value);
 
       /* store all but the type */
-      default_value.g_type = 0;
-      priv->default_value = default_value;
+      memcpy (priv->default_value.data, default_value.data, sizeof (default_value.data));
 
       g_once_init_leave (&priv->default_value.g_type, pspec->value_type);
     }
diff --git a/tests/refcount/properties.c b/tests/refcount/properties.c
index c68234216..376d9313c 100644
--- a/tests/refcount/properties.c
+++ b/tests/refcount/properties.c
@@ -35,7 +35,7 @@ struct _GTestClass
 };
 
 static GType my_test_get_type (void);
-static volatile gboolean stopping;
+static gboolean stopping;
 
 static void my_test_class_init (GTestClass * klass);
 static void my_test_init (GTest * test);
@@ -177,7 +177,7 @@ run_thread (GTest * test)
 {
   gint i = 1;
   
-  while (!stopping) {
+  while (!g_atomic_int_get (&stopping)) {
     my_test_do_property (test);
     if ((i++ % 10000) == 0)
       {
@@ -210,14 +210,14 @@ main (int argc, char **argv)
     g_signal_connect (test, "notify::dummy", G_CALLBACK (dummy_notify), NULL);
   }
 
-  stopping = FALSE;
+  g_atomic_int_set (&stopping, FALSE);
 
   for (i = 0; i < N_THREADS; i++)
     test_threads[i] = g_thread_create ((GThreadFunc) run_thread, test_objects[i], TRUE, NULL);
 
   g_usleep (3000000);
 
-  stopping = TRUE;
+  g_atomic_int_set (&stopping, TRUE);
   g_print ("\nstopping\n");
 
   /* join all threads */