diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index fd6557e7118a6774e81f17cca6a97b3ef8604287..fba259ab99941e429fa7c5f55fc3a42229778efa 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3310,7 +3310,7 @@ static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp)
 	}
 
 	if (!objectid)
-		objectid = root->root_key.objectid;
+		objectid = BTRFS_FS_TREE_OBJECTID;
 
 	location.objectid = objectid;
 	location.type = BTRFS_ROOT_ITEM_KEY;