On my mac (10.6.5) I'm running python2.6 with numpy 1.5.0. While using f2py with f2py -c --fcompiler=gnu95 --f77flags='-m32 -O1 -fno-second-underscore -fbounds-check' src/mars.pyf src/mars.f It compiles but has link warnings. -m32 is not being passed to gcc. ld: warning: in /var/folders/k-/k-SUt4dLGyWuiaA0fiYLOU++4GM/-Tmp-/tmp8xkKpp/var/folders/k-/k-SUt4dLGyWuiaA0fiYLOU++4GM/-Tmp-/tmp8xkKpp/src.macosx-10.6-i386-2.6/src/marsmodule.o, file was built for unsupported file format which is not the architecture being linked (i386) ld: warning: in /var/folders/k-/k-SUt4dLGyWuiaA0fiYLOU++4GM/-Tmp-/tmp8xkKpp/var/folders/k-/k-SUt4dLGyWuiaA0fiYLOU++4GM/-Tmp-/tmp8xkKpp/src.macosx-10.6-i386-2.6/fortranobject.o, file was built for unsupported file format which is not the architecture being linked (i386) Any help would be appreciated!!! Jim