diff --git a/gtk/gtkbutton.h b/gtk/gtkbutton.h
index 499615da98..bdfbfc0af8 100644
--- a/gtk/gtkbutton.h
+++ b/gtk/gtkbutton.h
@@ -60,15 +60,15 @@ struct _GtkButton
 
   guint activate_timeout;
 
-  guint constructed : 1;
-  guint in_button : 1;
-  guint button_down : 1;
-  guint relief : 2;
-  guint use_underline : 1;
-  guint use_stock : 1;
-  guint depressed : 1;
-  guint depress_on_activate : 1;
-  guint focus_on_click : 1;
+  guint GSEAL (constructed : 1);
+  guint GSEAL (in_button : 1);
+  guint GSEAL (button_down : 1);
+  guint GSEAL (relief : 2);
+  guint GSEAL (use_underline : 1);
+  guint GSEAL (use_stock : 1);
+  guint GSEAL (depressed : 1);
+  guint GSEAL (depress_on_activate : 1);
+  guint GSEAL (focus_on_click : 1);
 };
 
 struct _GtkButtonClass