Hi, I discovered a bug in split_winmain. If the wstring version of the function is used the result vector is always empty: Original code in libs/program_options/src/winmain.cpp: #ifndef BOOST_NO_STD_WSTRING BOOST_PROGRAM_OPTIONS_DECL std::vector<std::wstring> split_winmain(const std::wstring& cmdline) { vector<wstring> result; vector<string> aux = split_winmain(to_internal(cmdline)); for (unsigned i = 0, e = result.size(); i < e; ++i) result.push_back(from_utf8(aux[i])); return result; } #endif The expression result.size() in the for-loop has to be replaced with aux.size(). At least boost lib 1.33.0 and 1.33.1 contain this bug but I think nobody used the function for years... Best regards, Philipp