diff --git a/kern/start.c b/kern/start.c
index 3c9f0ba..ac0bcd2 100644
--- a/kern/start.c
+++ b/kern/start.c
@@ -9,6 +9,7 @@
 #include <panic.h>
 #include <proc.h>
 #include <riscv.h>
+#include <rtc.h>
 #include <spinlock.h>
 #include <stdint.h>
 #include <stdio.h>