diff --git a/osbase/net/dns/forward/cache/cache.go b/osbase/net/dns/forward/cache/cache.go
index 8c151a6..114939b 100644
--- a/osbase/net/dns/forward/cache/cache.go
+++ b/osbase/net/dns/forward/cache/cache.go
@@ -1,3 +1,6 @@
+// Copyright The Monogon Project Authors.
+// SPDX-License-Identifier: Apache-2.0
+
 // Package cache implements a cache. The cache hold 256 shards, each shard
 // holds a cache: a map with a mutex. There is no fancy expunge algorithm, it
 // just randomly evicts elements when it gets full.
diff --git a/osbase/net/dns/forward/cache/cache_test.go b/osbase/net/dns/forward/cache/cache_test.go
index 8a2b80c..5542158 100644
--- a/osbase/net/dns/forward/cache/cache_test.go
+++ b/osbase/net/dns/forward/cache/cache_test.go
@@ -1,3 +1,6 @@
+// Copyright The Monogon Project Authors.
+// SPDX-License-Identifier: Apache-2.0
+
 package cache
 
 // Taken and modified from CoreDNS, under Apache 2.0.
diff --git a/osbase/net/dns/forward/cache/shard_test.go b/osbase/net/dns/forward/cache/shard_test.go
index 452f8cc..f8e3153 100644
--- a/osbase/net/dns/forward/cache/shard_test.go
+++ b/osbase/net/dns/forward/cache/shard_test.go
@@ -1,3 +1,6 @@
+// Copyright The Monogon Project Authors.
+// SPDX-License-Identifier: Apache-2.0
+
 package cache
 
 // Taken and modified from CoreDNS, under Apache 2.0.