On Jul 18, 2022, at 1:44 AM, Andreas Schwab via tz <tz at iana.org> wrote: > You are not setting tm_gmtoff, thus it remains at zero. MacOS probably > doesn't have tm_gmtoff. Given that it's derived from, among other sources, various 4.4-Lite-derived BSDs, macOS most definitely *does* have tm_gmtoff.