Hi, Sorry for the n00b question, but I'm trying to serialize some unsigned __int64 member variables using boost::serialization. I added the following to my header: namespace boost { namespace serialization { template<class Archive> void load(Archive & ar, unsigned __int64& big, const unsigned int version) { size_t size = sizeof(big); ar.load_binary(&big, size); } template<class Archive> void save(Archive & ar, unsigned __int64 big, const unsigned int version) { ar & sizeof(big); ar.save_binary(&big, sizeof(big)); } } }; But the compiler still complains that it doesn't know how to handle that right-hand operand. Is there something obvious here I'm missing? Thanks -S