diff --git a/gtk/gtkentrycompletion.h b/gtk/gtkentrycompletion.h
index b9ad7ce2e8..14365ff613 100644
--- a/gtk/gtkentrycompletion.h
+++ b/gtk/gtkentrycompletion.h
@@ -55,7 +55,7 @@ struct _GtkEntryCompletion
   GObject parent_instance;
 
   /*< private >*/
-  GtkEntryCompletionPrivate *priv;
+  GtkEntryCompletionPrivate *GSEAL (priv);
 };
 
 struct _GtkEntryCompletionClass