I am porting the code from (boost44, msvc2008, Qt, unicode support) to (boost46, msvc2010, Qt, unicode support). I am getting following linker error: error LNK2001: unresolved external symbol "private: static class std::codecvt const * & __cdecl boost::filesystem3::path::wchar_t_codecvt_facet(void)" (? wchar_t_codecvt_facet@path@filesystem3@boost@@CAAAPBV?$codecvt@GDH@std@@XZ) I found that std::codecvt defined in <xlocale>. May be the filesystem lib should be built in certain way to support widestrings? Any advise/help will be greatly appreciated.