diff --git a/ChangeLog b/ChangeLog
index 53ff66c70..f9c0a3789 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2009-01-23 Richard Frith-Macdonald <rfm@gnu.org>
+
+	* Source/NSWindow.m: ignore invalid rects when checking
+	tracking rectangles.
+
 2009-01-23 Fred Kiefer <FredKiefer@gmx.de>
 
 	* Source/NSMenuView.m: Convert between the window and the view 
diff --git a/Source/NSWindow.m b/Source/NSWindow.m
index d31592952..e9841ff73 100644
--- a/Source/NSWindow.m
+++ b/Source/NSWindow.m
@@ -3275,6 +3275,8 @@ resetCursorRectsForView(NSView *theView)
               BOOL now;
               GSTrackingRect *r = rects[i];
 
+              if ([r isValid] == NO)
+                continue;
               /* Check mouse at last point */
               last = NSMouseInRect(_lastPoint, r->rectangle, NO);
               /* Check mouse at current point */