diff --git a/ssh/test/test_unix_test.go b/ssh/test/test_unix_test.go
index f44c65d..660f3d5 100644
--- a/ssh/test/test_unix_test.go
+++ b/ssh/test/test_unix_test.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 darwin freebsd linux netbsd openbsd
+// +build darwin freebsd linux netbsd openbsd plan9
 
 package test