diff --git a/src/core/timer.c b/src/core/timer.c
index d9ba2f76b3..0c1ca3ef23 100644
--- a/src/core/timer.c
+++ b/src/core/timer.c
@@ -380,6 +380,13 @@ static void timer_enter_waiting(Timer *t, bool time_change) {
                         if (r < 0)
                                 continue;
 
+                        /* To make the delay due to RandomizedDelaySec= work even at boot,
+                         * if the scheduled time has already passed, set the time when systemd
+                         * first started as the scheduled time.
+                         * Also, we don't have to check t->persistent since the logic implicitly express true. */
+                        if (v->next_elapse < UNIT(t)->manager->timestamps[MANAGER_TIMESTAMP_USERSPACE].realtime)
+                                v->next_elapse = UNIT(t)->manager->timestamps[MANAGER_TIMESTAMP_USERSPACE].realtime;
+
                         if (!found_realtime)
                                 t->next_elapse_realtime = v->next_elapse;
                         else