If the local time for which we want data is after the last known transition, the two transitions we get to bracket it are the last known and an invalid one. The code checked the former was valid, but neglected to check the latter, leading to nonsense arithmetic later in the function. In this situation we unequivocally want the last known transition, so the problem is easily solved. Fixes: QTBUG-96152 Pick-to: 6.2 6.1 5.15 5.12 Change-Id: I6fc830ce538e8a572093cd8dfe832e10689bf904 Reviewed-by: Andrei Golubev <andrei.golubev@qt.io> Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>