freebsd extension problem

[Robin Becker]

I'm trying to build an extension which used to work with 1.5.2 unde
freebsd.

I seem to be able to build the extension using the old

make -f Makefile.pre.in boot method and have linked to various
libraries. However for some reason I'm getting a bad magic number error
when trying to import the module.

I assume that this is somehow caused by a missing import. Is there an
easy way to find out what I'm missing?
-- 
Robin Becker