So this morning I decided to play with Digest::MD5 a bit, and lo, it was as Peter Prymmer (and then, this morning, Artur Bergman) suggested: a compiler optimization. D'oh. I thought that I had seen the same problem in MrC, but apparently I had not. So I tried setting MWCPPC to -O1, and it was fine. Heh. So now I just need to find a way to tell the build process to use -O1 for that file.