diff --git a/wgengine/router/runner.go b/wgengine/router/runner.go
index 59d85cef7..46332129f 100644
--- a/wgengine/router/runner.go
+++ b/wgengine/router/runner.go
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build linux
+
 package router
 
 import (