diff --git a/third_party/sandboxroot/tools.go b/third_party/sandboxroot/tools.go
index 578e592..8ca9f15 100644
--- a/third_party/sandboxroot/tools.go
+++ b/third_party/sandboxroot/tools.go
@@ -1,3 +1,6 @@
+// Copyright The Monogon Project Authors.
+// SPDX-License-Identifier: Apache-2.0
+
 //go:build tools
 // +build tools