I checked why it doesn't work on powerpc and it turns out it's actually an endianness problem. So I think the best way is to detect endianness with post-main { if { [string compare ${os.endian} "little"] != 0 } { ui_error "${name} only runs on little-endian machines." exit 1 } } I don't exactly know how many different platforms the port system is supposed to work on so I think it's preferable to check it this way rather than listing all the platforms. Still, I haven't found a single port using post-main, but I haven't found a port that only work on a specific endianness, so the question remains: is it acceptable to test compatibility with this post-main script ? Anyway, I have posted an updated portfile: http://trac.macports.org/ projects/macports/attachment/ticket/11114/Portfile_v2 Cédric