diff --git a/test/common/markdown/gulpfile.js b/test/common/markdown/gulpfile.js
index 4da3762d063..e50f9f142a0 100644
--- a/test/common/markdown/gulpfile.js
+++ b/test/common/markdown/gulpfile.js
@@ -1,3 +1,4 @@
+"use strict";
 var gulp = require("gulp");
 var concat = require("gulp-concat");
 var through2 = require("through2");