diff --git a/build/lib/reporter.js b/build/lib/reporter.js
index 307a689defd..d9a7de331f4 100644
--- a/build/lib/reporter.js
+++ b/build/lib/reporter.js
@@ -3,6 +3,8 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
+'use strict';
+
 const es = require('event-stream');
 const _ = require('underscore');
 const util = require('gulp-util');