diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 3ad497f..1fa2654 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -14,6 +14,7 @@
 #include <linux/seq_file.h>
 #include <linux/kdev_t.h>
 #include <linux/module.h>
+#include <linux/err.h>
 #include "blk-cgroup.h"
 
 static DEFINE_SPINLOCK(blkio_list_lock);