It seems that there should be a way to get 64-bit integer support into integer_traits.hpp on MSVC. It looks like the only real problem is the missing feature of class constants, and the fact that integer_traits is using enums (which can't hold const_max and const_min values). But if there were specializations on the detail::integer_traits_base for MS 64-bit types, the constants could be declared in-class as __int64 but defined out-of-class (still in the header), safely. It's not as pretty as BOOST_STATIC_CONSTANT, but wouldn't it work? john harris trading technologies