I thought I'd write a simple physics BSD library but have a slight problem. I want to work on it with my Dad but his computer is a 32bit Intel Mac Mini while mine is the 2006 Mac Pro. I need to use GMP which compiles as 64bit (even if I tell it to use a 32bit ABI) on my machine and 32bit on my Dads. We would be working together via SVN which is hosted on my machine. Am I just being stupid with this problem? I thought about trying to build a 64 and 32bit version on my machine and just have Dad compile the 32bit version but that brings in problems with versioning etc. Plus I'm not quite sure of SVN, I've never used it for working on a project with someone. Any suggestions?