diff --git a/gtk/gtkdialog.h b/gtk/gtkdialog.h
index 17f0503ac4..392d1aba69 100644
--- a/gtk/gtkdialog.h
+++ b/gtk/gtkdialog.h
@@ -67,7 +67,7 @@ typedef enum
  * @GTK_RESPONSE_HELP: Returned by Help buttons in GTK+ dialogs
  *
  * Predefined values for use as response ids in gtk_dialog_add_button().
- * All predefined values are negative, GTK+ leaves positive values for
+ * All predefined values are negative; GTK+ leaves values of 0 or greater for
  * application-defined response ids.
  */
 typedef enum