diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index b391335..c22a61f 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -24,7 +24,8 @@
 int close_ctree(struct btrfs_root *root, struct btrfs_super_block *s);
 void btrfs_block_release(struct btrfs_root *root, struct btrfs_buffer *buf);
 int write_ctree_super(struct btrfs_root *root, struct btrfs_super_block *s);
-int mkfs(int fd);
+int mkfs(int fd, u64 num_blocks, u16 blocksize);
+
 
 #define BTRFS_SUPER_INFO_OFFSET(bs) (16 * (bs))