diff --git a/src/sfptpd_clock.c b/src/sfptpd_clock.c
index 6fd66723..43bdd32f 100644
--- a/src/sfptpd_clock.c
+++ b/src/sfptpd_clock.c
@@ -1095,7 +1095,8 @@ static void clock_record_step(void)
 	clock_lock();
 	for (clock = sfptpd_clock_list_head; clock != NULL; clock = clock->next) {
 		assert(clock->magic == SFPTPD_CLOCK_MAGIC);
-		if (clock->type != SFPTPD_CLOCK_TYPE_SYSTEM)
+		if (clock->type != SFPTPD_CLOCK_TYPE_SYSTEM &&
+		    clock->u.nic.phc != NULL)
 			sfptpd_phc_record_step(clock->u.nic.phc);
 	}
 	clock_unlock();