Andrei Alexandrescu wrote: > ulong t = (dt - ticksFrom1601To1970) * (10_000_000 / > TicksPerSecond); That must be addition, otherwise I go back in time to 1200 or so. Now everything works, thanks to all who answered. The upside of all this is that now setFileTimes works on both Windows and Posix. :o) Andrei