Patrick Mauritz wrote: #define BOOST_PYTHON_OFFSETOF(s_name, s_member) \ (__offsetof__ (reinterpret_cast <size_t> (&reinterpret_cast <const volatile char &> (static_cast<s_name *> (0)->s_member)))) in boost/python/detail/config.hpp fixes things Is this GCC version specific? Kind regards, Henry