diff --git a/gdk/gdkcontentdeserializer.c b/gdk/gdkcontentdeserializer.c
index 081380f447..a9a1d08a9c 100644
--- a/gdk/gdkcontentdeserializer.c
+++ b/gdk/gdkcontentdeserializer.c
@@ -264,7 +264,7 @@ gdk_content_deserializer_get_priority (GdkContentDeserializer *deserializer)
  *
  * This is the `GCancellable` that was passed to [func@Gdk.content_deserialize_async].
  *
- * Returns: (transfer none): the cancellable for the current operation
+ * Returns: (transfer none) (nullable): the cancellable for the current operation
  */
 GCancellable *
 gdk_content_deserializer_get_cancellable (GdkContentDeserializer *deserializer)
diff --git a/gdk/gdkcontentserializer.c b/gdk/gdkcontentserializer.c
index 75734e2765..3d1295b33e 100644
--- a/gdk/gdkcontentserializer.c
+++ b/gdk/gdkcontentserializer.c
@@ -270,7 +270,7 @@ gdk_content_serializer_get_priority (GdkContentSerializer *serializer)
  *
  * This is the `GCancellable` that was passed to [func@content_serialize_async].
  *
- * Returns: (transfer none): the cancellable for the current operation
+ * Returns: (transfer none) (nullable): the cancellable for the current operation
  */
 GCancellable *
 gdk_content_serializer_get_cancellable (GdkContentSerializer *serializer)
diff --git a/gdk/gdkevents.c b/gdk/gdkevents.c
index e577c6b9c0..1f4a920720 100644
--- a/gdk/gdkevents.c
+++ b/gdk/gdkevents.c
@@ -1225,7 +1225,7 @@ gdk_event_get_event_type (GdkEvent *event)
  *
  * Extracts the surface associated with an event.
  *
- * Returns: (transfer none): The `GdkSurface` associated with the event
+ * Returns: (transfer none) (nullable): The `GdkSurface` associated with the event
  */
 GdkSurface *
 gdk_event_get_surface (GdkEvent *event)
diff --git a/gdk/gdkpopup.c b/gdk/gdkpopup.c
index a71e63d57e..4dd97ac7ad 100644
--- a/gdk/gdkpopup.c
+++ b/gdk/gdkpopup.c
@@ -187,7 +187,7 @@ gdk_popup_get_rect_anchor (GdkPopup *popup)
  *
  * Returns the parent surface of a popup.
  *
- * Returns: (transfer none): the parent surface
+ * Returns: (transfer none) (nullable): the parent surface
  */
 GdkSurface *
 gdk_popup_get_parent (GdkPopup *popup)
diff --git a/gdk/x11/gdksurface-x11.c b/gdk/x11/gdksurface-x11.c
index 4e2c2e9e11..8567d83eb8 100644
--- a/gdk/x11/gdksurface-x11.c
+++ b/gdk/x11/gdksurface-x11.c
@@ -3535,7 +3535,7 @@ gdk_x11_surface_unfullscreen (GdkSurface *surface)
  *
  * Returns the group this surface belongs to.
  *
- * Returns: (transfer none): The group of this surface;
+ * Returns: (transfer none) (nullable): The group of this surface;
  */
 GdkSurface *
 gdk_x11_surface_get_group (GdkSurface *surface)