diff --git a/sched/clock/clock_settime.c b/sched/clock/clock_settime.c
index 02687b95864..1f352e6bb47 100644
--- a/sched/clock/clock_settime.c
+++ b/sched/clock/clock_settime.c
@@ -77,7 +77,8 @@ int clock_settime(clockid_t clock_id, FAR const struct timespec *tp)
    * time clock.
    */
 
-  if (clock_id == CLOCK_REALTIME)
+  if (clock_id == CLOCK_REALTIME &&
+      tp->tv_nsec >= 0 && tp->tv_nsec < 1000000000)
     {
 #ifndef CONFIG_CLOCK_TIMEKEEPING
       /* Interrupts are disabled here so that the in-memory time