diff --git a/metropolis/node/net_protocols.go b/metropolis/node/net_protocols.go
index 26dd0c0..f3e69b8 100644
--- a/metropolis/node/net_protocols.go
+++ b/metropolis/node/net_protocols.go
@@ -1,3 +1,6 @@
+// Copyright The Monogon Project Authors.
+// SPDX-License-Identifier: Apache-2.0
+
 package node
 
 // These are netlink protocol numbers used internally for various netlink