diff --git a/xds/internal/client/bootstrap/bootstrap_test.go b/xds/internal/client/bootstrap/bootstrap_test.go
index 6190ccb5f9b4..d450d718c74c 100644
--- a/xds/internal/client/bootstrap/bootstrap_test.go
+++ b/xds/internal/client/bootstrap/bootstrap_test.go
@@ -1,3 +1,5 @@
+// +build go1.10
+
 /*
  *
  * Copyright 2019 gRPC authors.