diff --git a/src/core/frame.c b/src/core/frame.c
index 529a7c655..23bb6e106 100644
--- a/src/core/frame.c
+++ b/src/core/frame.c
@@ -386,7 +386,7 @@ void
 meta_frame_get_mask (MetaFrame                    *frame,
                      cairo_t                      *cr)
 {
-  meta_ui_frame_get_mask (frame->ui_frame, frame->rect.width, frame->rect.height, cr);
+  meta_ui_frame_get_mask (frame->ui_frame, cr);
 }
 
 void
diff --git a/src/ui/frames.c b/src/ui/frames.c
index 347dcd03e..83378c3fc 100644
--- a/src/ui/frames.c
+++ b/src/ui/frames.c
@@ -1487,30 +1487,27 @@ get_visible_frame_border_region (MetaUIFrame *frame)
  *
  * @frame: This frame
  * @xwindow: The X window for the frame, which has the client window as a child
- * @width: The width of the framed window including any invisible borders
- * @height: The height of the framed window including any invisible borders
  * @cr: Used to draw the resulting mask
  */
 void
 meta_ui_frame_get_mask (MetaUIFrame *frame,
-                        guint        width,
-                        guint        height,
                         cairo_t     *cr)
 {
   MetaFrameBorders borders;
   MetaFrameFlags flags;
+  MetaRectangle frame_rect;
 
   meta_core_get (GDK_DISPLAY_XDISPLAY (gdk_display_get_default ()),
                  frame->xwindow,
                  META_CORE_GET_FRAME_FLAGS, &flags,
+                 META_CORE_GET_FRAME_RECT, &frame_rect,
                  META_CORE_GET_END);
 
   meta_style_info_set_flags (frame->style_info, flags);
   meta_ui_frame_get_borders (frame, &borders);
   gtk_render_background (frame->style_info->styles[META_STYLE_ELEMENT_FRAME], cr,
                          borders.invisible.left, borders.invisible.top,
-                         width - borders.invisible.left - borders.invisible.right,
-                         height - borders.invisible.top - borders.invisible.bottom);
+                         frame_rect.width, frame_rect.height);
 }
 
 /* XXX -- this is disgusting. Find a better approach here.
diff --git a/src/ui/frames.h b/src/ui/frames.h
index 66c72a01e..139cb36e3 100644
--- a/src/ui/frames.h
+++ b/src/ui/frames.h
@@ -140,8 +140,6 @@ cairo_region_t * meta_ui_frame_get_bounds (MetaUIFrame *frame,
                                            int          window_height);
 
 void meta_ui_frame_get_mask (MetaUIFrame *frame,
-                             guint        width,
-                             guint        height,
                              cairo_t     *cr);
 
 void meta_ui_frame_move_resize (MetaUIFrame *frame,