Bingo! 1.5.2 links with -lieee while 2.0 doesn't. Removing -lieee from the 1.5.2 link line makes is raise OverflowError too. Adding it to the 2.0 link line makes it return 0.0 for exp(-1000) and inf for exp(1000). Next question: what changed in the configure script, and why? --Guido van Rossum (home page: http://www.python.org/~guido/)