diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index 197208b..3b606d3 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -290,7 +290,8 @@
 		info->si_overrun = timr->it_overrun_last;
 	}
 
-	unlock_timer(timr, flags);
+	if (timr)
+		unlock_timer(timr, flags);
 }
 
 int posix_timer_event(struct k_itimer *timr,int si_private)