It's actually seconds since epoch, not milliseconds. Here's a small program to verify it: date -u --date='2038-01-19T03:14:08' +%s | perl -ne 'printf "%#x\n"

It's actually seconds since epoch, not milliseconds. Here's a small program to verify it: date -u --date='2038-01-19T03:14:08' +%s | perl -ne 'printf "%#x\n", $_' It is also mentioned in perldoc Time::Piece [1], as a warning for people whose build of perl uses 32-bit integers for time. [1]: https://perldoc.perl.org/Time::Piece#Use-of-epoch-seconds https://perldoc.perl.org/Time::Piece#Use-of-epoch-seconds