--- a/widget/tests/native_mouse_mac_window.xul
+++ b/widget/tests/native_mouse_mac_window.xul
@@ -379,17 +379,17 @@
             callback();
           });
         },
         // Now the tooltip is visible.
         // Move the mouse a little to the right, but send the event to the tooltip's
         // widget, even though the mouse is not over the tooltip, because that's what
         // Mac OS X does.
         [411, 180, NSMouseMoved, tooltip, right, [
-          { type: "mousemove", target: rightElem },
+          { type: "mousemove", target: rightElem, todoShouldNotHaveFired: !!navigator.oscpu.match(/Mac OS X 10\.6$/) },
         ]],
         // Move another pixel. This time send the event to the right widget.
         // However, that must not make a difference.
         [412, 180, NSMouseMoved, null, right, [
           { type: "mousemove", target: rightElem },
         ]],
         // Move up and click to make the tooltip go away.
         [412, 80, NSMouseMoved, null, right, [