Broken Wheel Lock nut

I have a 2002 Impala LS. I was changing one of the front tires and the wheel lock nut cracked. This is an original GM lock nut. Car is no longer under warranty. Anyone have any idea as to how to remove the bolt? The thread on the wheel stud is still fine.

Thanks!

My car had those and with prior experience...it was one of the first things I did. I bought regular lug nuts, took all the lock nut things off and put them on. Being me, i would use a pipe wrench to break it loose and then from there you should be able to twist them off by hand...

mike