diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c
index 84e6781..902ce50 100644
--- a/fs/btrfs/delayed-ref.c
+++ b/fs/btrfs/delayed-ref.c
@@ -17,6 +17,7 @@
  */
 
 #include <linux/sched.h>
+#include <linux/slab.h>
 #include <linux/sort.h>
 #include "ctree.h"
 #include "delayed-ref.h"