diff --git a/src/index.js b/src/index.js
index 6e742b15b..9eb8d9b1f 100755
--- a/src/index.js
+++ b/src/index.js
@@ -1,3 +1,5 @@
+'use strict';
+
 module.exports = require('./ServerlessOffline.js');
 
 // Serverless exits with code 1 when a promise rejection is unhandled. Not AWS.