diff --git a/fs/nilfs2/mdt.c b/fs/nilfs2/mdt.c
index 06713ff..024be8c 100644
--- a/fs/nilfs2/mdt.c
+++ b/fs/nilfs2/mdt.c
@@ -26,6 +26,7 @@
 #include <linux/writeback.h>
 #include <linux/backing-dev.h>
 #include <linux/swap.h>
+#include <linux/slab.h>
 #include "nilfs.h"
 #include "segment.h"
 #include "page.h"