diff --git a/gio/gsocketcontrolmessage.c b/gio/gsocketcontrolmessage.c
index 72e81ff00..398e04e5e 100644
--- a/gio/gsocketcontrolmessage.c
+++ b/gio/gsocketcontrolmessage.c
@@ -164,7 +164,7 @@ g_socket_control_message_class_init (GSocketControlMessageClass *class)
  * If there is no implementation for this kind of control message, %NULL
  * will be returned.
  *
- * Returns: (transfer full): the deserialized message or %NULL
+ * Returns: (nullable) (transfer full): the deserialized message or %NULL
  *
  * Since: 2.22
  */