diff --git a/Gruntfile.js b/Gruntfile.js
index 1a0531b9f1..5ba8abbfb9 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -195,6 +195,7 @@ module.exports = function (grunt) {
       options: {
         charset: 'utf-8',
         doctype: 'HTML5',
+        failHard: true,
         reset: true,
         relaxerror: [
           'Bad value X-UA-Compatible for attribute http-equiv on element meta.',