http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48340
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-03-29 17:52:44 UTC --- Here's a simpler test, which should return 1: #include <locale> int main() { return isspace(L' ', std::locale()); } if that works, how about this, which should also return 1: #include <locale> #include <sstream> #include <string> int main() { std::wstring s(L" "); std::wistringstream ss; return isspace(s[0], ss.getloc()); }