diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index eec50fcef9e4..88c9c65a430d 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -490,7 +490,7 @@ static int alarm_clock_getres(const clockid_t which_clock, struct timespec *tp)
 	clockid_t baseid = alarm_bases[clock2alarm(which_clock)].base_clockid;
 
 	if (!alarmtimer_get_rtcdev())
-		return -ENOTSUPP;
+		return -EINVAL;
 
 	return hrtimer_get_res(baseid, tp);
 }
@@ -507,7 +507,7 @@ static int alarm_clock_get(clockid_t which_clock, struct timespec *tp)
 	struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
 
 	if (!alarmtimer_get_rtcdev())
-		return -ENOTSUPP;
+		return -EINVAL;
 
 	*tp = ktime_to_timespec(base->gettime());
 	return 0;