diff --git a/gdk/x11/gdkdrag-x11.c b/gdk/x11/gdkdrag-x11.c
index 8ac9bd782b..9f2327b813 100644
--- a/gdk/x11/gdkdrag-x11.c
+++ b/gdk/x11/gdkdrag-x11.c
@@ -1786,7 +1786,7 @@ gdk_drag_anim_timeout (gpointer data)
                         (drag->start_x - drag->last_x) * t,
                         (drag->last_y - drag->hot_y) +
                         (drag->start_y - drag->last_y) * t);
-  gdk_surface_set_opacity (drag->drag_surface, 1.0 - f);
+  gdk_x11_surface_set_opacity (drag->drag_surface, 1.0 - f);
 
   return G_SOURCE_CONTINUE;
 }
diff --git a/gdk/x11/gdkprivate-x11.h b/gdk/x11/gdkprivate-x11.h
index d1b5e4c3e3..b97913de6d 100644
--- a/gdk/x11/gdkprivate-x11.h
+++ b/gdk/x11/gdkprivate-x11.h
@@ -231,6 +231,8 @@ void gdk_x11_surface_get_root_coords (GdkSurface *surface,
                                       gint       *root_y);
 
 void gdk_x11_surface_raise (GdkSurface *surface);
+void gdk_x11_surface_set_opacity (GdkSurface *surface,
+                                  double      opacity);
 
 GdkGrabStatus _gdk_x11_convert_grab_status (gint status);
 
diff --git a/gdk/x11/gdksurface-x11.c b/gdk/x11/gdksurface-x11.c
index ab65449f2b..1102bbf869 100644
--- a/gdk/x11/gdksurface-x11.c
+++ b/gdk/x11/gdksurface-x11.c
@@ -4459,9 +4459,9 @@ gdk_x11_surface_beep (GdkSurface *surface)
   return FALSE;
 }
 
-static void
+void
 gdk_x11_surface_set_opacity (GdkSurface *surface,
-			    gdouble    opacity)
+			     double      opacity)
 {
   GdkDisplay *display;
   gulong cardinal;