diff --git a/kernel/mutex.c b/kernel/mutex.c
index a307cc9..52f2301 100644
--- a/kernel/mutex.c
+++ b/kernel/mutex.c
@@ -19,6 +19,7 @@
  */
 #include <linux/mutex.h>
 #include <linux/sched.h>
+#include <linux/sched/rt.h>
 #include <linux/export.h>
 #include <linux/spinlock.h>
 #include <linux/interrupt.h>