I've been through that as well. I have in the past just provided a different Makefile for each platform and run as follows: make -f Makefile.osf1 make

I've been through that as well. I have in the past just provided a different Makefile for each platform and run as follows: make -f Makefile.osf1 make -f Makefile.sunos4 make -f Makefile.sunos5 There is usually little difference between them - mainly compiler names/flags and the occasional def for code. Occasionally make is broken at which point you have to frig something. Keep It Simple is the #1 rule. Rule #2 is every bad thing you do will do two things bad back to you in the future.