metis conflict problem

when I compiled my program I got this error message

/home/haowei/workspace/MDMetis/Lib/proto.h:462: error: declaration of C function ‘int __log2(int)’ conflicts with
/usr/include/bits/mathcalls.h:145: error: previous declaration ‘double __log2(double)’ here

Could somebody please tell me what is wrong with the metis library or my setting? Thank you very much.

PS: I downloaded metis4.0 and my compiler is gcc 4.3.0 , mpich-1.08 ,OS : linux version