diff --git a/app.js b/app.js
index 4c4fe56e37..1b3a2324ba 100644
--- a/app.js
+++ b/app.js
@@ -1,3 +1,5 @@
+'use strict;
+
 const createError = require('http-errors');
 const express = require('express');
 const path = require('path');