} // namespace lyx
-#if SIZEOF_WCHAR_T != 4 && defined(__GNUC__) && defined(__GNUC_MINOR__) && __GNUC__ == 3 && __GNUC_MINOR__ < 4
+#if ! defined(USE_WCHAR_T) && defined(__GNUC__) && defined(__GNUC_MINOR__) && __GNUC__ == 3 && __GNUC_MINOR__ < 4
// Missing char_traits methods in gcc 3.3 and older. Taken from gcc 4.2svn.
namespace std {