diff --git a/index.js b/index.js
index 318d3d3..c1d4bd2 100644
--- a/index.js
+++ b/index.js
@@ -1,6 +1,8 @@
 //https://github.com/angular/angular.js/pull/10732
 
-var angular = require('angular');
+if (typeof angular !== 'undefined') {
+  var angular = require('angular');
+}
 var mask = require('./dist/mask');
 
 module.exports = 'ui.mask';