Greetings, I think I catched a bug related to the day-light saving gap: *uname -a ; date ; date -d "2020/06/01 10:00:00 +1 hours"* Linux ******** 4.19.0-8-amd64 #1 SMP Debian 4.19.98-1 (2020-01-26) x86_64 GNU/Linux miƩ nov 25 10:30:29 CET 2020 lun jun 1 *12*:00:00 CEST 2020 As far as I think it should work, the expected result should be: lun jun 1 *11*:00:00 CEST 2020 "One hour after 10" is 11, not 12. I'm not sure if it has something to do to be right now in UTC+1 and the other time un UTC+2, but I don't remember having any trouble while in DL saving while on UTC+2. To me, the intuitive way is the one the program worries about whether DL saving was/will be ON on the specified time. *date --version* date (GNU coreutils) 8.30 Copyright (C) 2018 Free Software Foundation, Inc. *lsb_release -a* No LSB modules are available. Distributor ID: Debian Description: Debian GNU/Linux 10 (buster) Release: 10 Codename: buster Thanks for your time, Ruder Laplace.