Hi, I currently use Visual 2005 and boost 1.34.1 revision On Win32 already is fine but when I migrate to Win64 Somewhere in my code (the location it’s not important) I have an assert compilation error due to definition of long int/unisgned (64 bits) windows i.e. see concept_check.hpp (ligne 149): template <class T> struct IntegerConcept { //// }; #if !defined BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION //// template <> struct IntegerConcept<unsigned long> { void constraints() {} }; // etc. <----- Pbs here ************************************ //Change here #ifdef _WIN64 template <> struct IntegerConcept<__int64> { void constraints() {} }; template <> struct IntegerConcept<unsigned __int64> { void constraints() {} }; #endif ************************************ #endif When I put this two lines, the code compile and link has well has on Win32 platform May I misunderstood something Or a better solution exist Thanks