diff --git a/pubsub/pubsub_mock.go b/pubsub/pubsub_mock.go
index 1a5e5be66..7a4e47156 100644
--- a/pubsub/pubsub_mock.go
+++ b/pubsub/pubsub_mock.go
@@ -3,6 +3,8 @@
 // Licensed under the MIT License.
 // ------------------------------------------------------------
 
+// +build test
+
 package pubsub
 
 import (