diff --git a/fs/ntfs3/fsntfs.c b/fs/ntfs3/fsntfs.c
index 3de5700a9b83..891125ca6848 100644
--- a/fs/ntfs3/fsntfs.c
+++ b/fs/ntfs3/fsntfs.c
@@ -831,10 +831,15 @@ int ntfs_update_mftmirr(struct ntfs_sb_info *sbi, int wait)
 {
 	int err;
 	struct super_block *sb = sbi->sb;
-	u32 blocksize = sb->s_blocksize;
+	u32 blocksize;
 	sector_t block1, block2;
 	u32 bytes;
 
+	if (!sb)
+		return -EINVAL;
+
+	blocksize = sb->s_blocksize;
+
 	if (!(sbi->flags & NTFS_FLAGS_MFTMIRR))
 		return 0;