Overlapping movieclips and rollovers

I have a small movieclip (button) sitting on top of a larger movieclip. The larger movieclip has an onRollOver and onRollOut event attached to it. Unfortunately that gets fired as well when I move the cursor over the button movieclip which is not desired. Is there a way to ignore that small movieclip for the rollover / rollout events?

I tried a mouse position check, but that doesn’t work too well when you move the mouse very fast, even with increased framerates. There must be an easier way I think.

Any ideas?