diff --git a/clutter/wayland/clutter-wayland-surface.h b/clutter/wayland/clutter-wayland-surface.h
index e5f64a127..1d7b0c7ce 100644
--- a/clutter/wayland/clutter-wayland-surface.h
+++ b/clutter/wayland/clutter-wayland-surface.h
@@ -81,6 +81,10 @@ struct _ClutterWaylandSurfaceClass
                                gint y,
                                gint width,
                                gint height);
+
+  /*< private >*/
+  /* padding for future expansion */
+  gpointer _padding_dummy[8];
 };
 
 GType clutter_wayland_surface_get_type (void) G_GNUC_CONST;