diff --git a/fs/namespace.c b/fs/namespace.c
index 8bd3e4d448b9..5a4438445bf7 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3488,6 +3488,8 @@ static int mntns_install(struct nsproxy *nsproxy, struct ns_common *ns)
 		return err;
 	}
 
+	put_mnt_ns(old_mnt_ns);
+
 	/* Update the pwd and root */
 	set_fs_pwd(fs, &root);
 	set_fs_root(fs, &root);