IO::Zlib is known to not be supported on 5.005, and it also appears to have a dependency on Compress::Zlib that is newer than 1.42... SO! Changes to the Makefile.PL as follows. Compress::Zlib dependency to 2.007. Perl dependency to 5.006, which is to say... use 5.006; at the top of the Makefile.PL.