diff --git a/build/toolbase/workspace.go b/build/toolbase/workspace.go
index f1d9f08..5213504 100644
--- a/build/toolbase/workspace.go
+++ b/build/toolbase/workspace.go
@@ -1,3 +1,6 @@
+// Copyright The Monogon Project Authors.
+// SPDX-License-Identifier: Apache-2.0
+
 package toolbase
 
 import (