There seems to be a problem on win32 where if you use a stream opened in text mode for a binary archive, you get errors. The following code asserts because 'd' appears to have a random value on the way back in. If you open both streams in binary mode then the code runs fine. XML archives don't have the same problem. I realise you shouldn't use a binary archive with a text stream, but is there anyway to catch this at compile or run time? Otherwise you just end up with a corrupted archive? Thanks Russell double d = -6.7; { ofstream ofs("C:\\test.dat"); archive::binary_oarchive oa(ofs); oa & d; } d = 0.0; { ifstream ifs("C:\\test.dat"); archive::binary_iarchive ia(ifs); ia & d; } assert(std::abs(d + 6.7) < 0.0001);