Hello! As shown in http://tinyurl.com/2q5xe that program_options fails unicode_test_dll on darwin. It's the only failure there, does not happen with statically linked version, and happens at runtime. For some reason conversion from or to unicode fails. Since it's runtime failure, I have no idea what could be wrong, and why it only happens in DLL. I'd really appreciate if somebody has a clue. Even knowning what's being converted, and at which character the codecvt facet fails might help. Thanks in advance, Volodya