diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index 667b0d107f..497554355a 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -11380,8 +11380,7 @@ gtk_widget_activate_action_variant (GtkWidget  *widget,
  * gtk_widget_activate_action:
  * @widget: a `GtkWidget`
  * @name: the name of the action to activate
- * @format_string: GVariant format string for arguments or %NULL
- *   for no arguments
+ * @format_string: (nullable): GVariant format string for arguments
  * @...: arguments, as given by format string
  *
  * Looks up the action in the action groups associated