log_debug_unit(UNIT(t)->id,
"%s: Monotonic timer elapses in %s the next time.",
UNIT(t)->id,
- format_timespan(buf, sizeof(buf), t->next_elapse_monotonic - ts.monotonic));
+ format_timespan(buf, sizeof(buf), t->next_elapse_monotonic > ts.monotonic ? t->next_elapse_monotonic - ts.monotonic : 0));
r = unit_watch_timer(UNIT(t), CLOCK_MONOTONIC, false, t->next_elapse_monotonic, &t->monotonic_watch);
if (r < 0)