As disccussed in the code review. Replace negative values with 1ms (not 0ms as that would spin up the event-loop too many times). Move QTimer::start(std::chrono::milliseconds msec) API docs next to the method definition so as to not forget changing it when the implementation changes. Drive-by, qWarning() and co. are marked cold so there is no need to use Q_UNLIKELY in an if-condition leading to calling these methods. [ChangeLog][QtCore][Important Behvaior Change] Timers with negative intervals aren't allowed anymore, that is, if you try to start a timer (or set the interval) with a negative value, that interval will be set to 1ms. Previously Qt timers would let you set the interval to a negative value, but behave in surprising ways (for example stop the timer if it was running or not start it at all). This change affects QTimer, QChronoTimer, QBasicTimer and QObject::startTimer(). Fixes: QTBUG-132359 Change-Id: I09309063665db051337f91160971993d9ce7911e Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>