diff --git a/gulpfile.js b/gulpfile.js
index da07e6ce..7f88a219 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -1,3 +1,5 @@
+'use strict';
+
 var gulp = require('gulp');
 var plugins = require('gulp-load-plugins')();
 var del = require('del');