(Sorry for sending this twice, I didn't format the subject the correct way first time) Hi, I'm using Visual Studio 2005 and got into trouble when I tried to serialize a class with 16 byte alignment: __declspec(align(16)) class Vech { ... __m128 m_data; }; The problem is that the following static assert in type_with_alignment is triggered: BOOST_STATIC_ASSERT(found % Align == 0); which in turn stems from the fact that sizeof(max_align) == 8. By changing the lines: #define BOOST_TT_ALIGNMENT_BASE_TYPES BOOST_PP_TUPLE_TO_LIST( \ 12, ( \ char, short, int, long, ::boost::long_long_type, float, double, long double \ , void*, function_ptr, member_ptr, member_function_ptr)) to #include <xmmintrin.h> #define BOOST_TT_ALIGNMENT_BASE_TYPES BOOST_PP_TUPLE_TO_LIST( \ 13, ( \ char, short, int, long, ::boost::long_long_type, float, double, long double \ , void*, function_ptr, member_ptr, member_function_ptr, __m128)) I got rid of the static assert and everything seems to work just fine. Would it be possible to get this "fix" into a later release of boost in a more rigorous and organized fashion (with all the surrounding compiler workarounds and typedefs etc.)? Or is there another way to get the same effect? Regards /A.B.