diff --git a/gtk/gtktoolitem.c b/gtk/gtktoolitem.c
index c877985496..9d145918f6 100644
--- a/gtk/gtktoolitem.c
+++ b/gtk/gtktoolitem.c
@@ -1299,7 +1299,7 @@ gtk_tool_item_retrieve_proxy_menu_item (GtkToolItem *tool_item)
  * @menu_item_ids must match ensures that a #GtkToolItem
  * will not inadvertently change a menu item that they did not create.
  *
- * Returns: (transfer none): The #GtkMenuItem passed to
+ * Returns: (transfer none) (nullable): The #GtkMenuItem passed to
  *     gtk_tool_item_set_proxy_menu_item(), if the @menu_item_ids
  *     match.
  *
@@ -1349,7 +1349,7 @@ gtk_tool_item_rebuild_menu (GtkToolItem *tool_item)
 
 /**
  * gtk_tool_item_set_proxy_menu_item:
- * @tool_item: a #GtkToolItem
+ * @tool_item: (nullable): a #GtkToolItem
  * @menu_item_id: a string used to identify @menu_item
  * @menu_item: a #GtkMenuItem to be used in the overflow menu
  *