diff --git a/root_stub.go b/root_stub.go
index 18dcb02..d00493a 100644
--- a/root_stub.go
+++ b/root_stub.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build plan9
+// +build plan9 darwin/nocgo
 
 package tls