I am using the portable style boost headers for tr1 implementation from Boost 1.42 such as #include <boost/tr1/type_traits.hpp> When i use gcc implementation of tr1 (Mingw GCC 4.5.1 from TDM, BOOST_HAS_GCC_TR1 defined) everything works fine. However when i select boost tr1 implementation (i.e not define the above macro) some stdlib functions such as std::abs gets wrong overloaded selected. For. e.g. in gcc/tr1 std::abs((signed char)5) returns an int while in boost/tr1 it returns a double. A compilable example is like #include <cstdlib> #include <iostream> #include <typeinfo> #include <boost/tr1/type_traits.hpp> int main(){ std::cout<<typeid(std::abs((short)5)).name(); //prints i with gcc/tr1 while prints d with boost/tr1 } it happens with type_traits header (may be few other also) but not with all tr1 headers(such as array). Thank you. abir basak