diff --git a/gio/gmenumodel.h b/gio/gmenumodel.h
index a97d7510f..5a94999ad 100644
--- a/gio/gmenumodel.h
+++ b/gio/gmenumodel.h
@@ -42,6 +42,16 @@ G_BEGIN_DECLS
  **/
 #define G_MENU_ATTRIBUTE_ACTION "action"
 
+/**
+ * G_MENU_ATTRIBUTE_ACTION_NAMESPACE:
+ *
+ * The menu item attribute that holds the namespace for all action names in
+ * menus that are linked from this item.
+ *
+ * Since: 2.36
+ **/
+#define G_MENU_ATTRIBUTE_ACTION_NAMESPACE "action-namespace"
+
 /**
  * G_MENU_ATTRIBUTE_TARGET:
  *