So last week even after trying again, I was still getting a compile error (as above). I managed to fix it by using 'PTR64=1', but now today I'm having the same problem with MESS again, whereby MAME is compiling fine (although yesterday MAME would not compile - same error as I was getting with MESS). The problem also is that the file that can't be compiled I don't think actually exists? Each time I try I get the same error, but the file name is different (dms.a, marrow.a and now this time it's be.a). I've tried both with and without 'PTR64=1' but no success.