diff --git a/include/linux/sem.h b/include/linux/sem.h
index 106f975..3c1f112 100644
--- a/include/linux/sem.h
+++ b/include/linux/sem.h
@@ -79,6 +79,8 @@
 
 #ifdef __KERNEL__
 
+struct task_struct;
+
 /* One semaphore structure for each semaphore in the system. */
 struct sem {
 	int	semval;		/* current value */