diff --git a/underscore.js b/underscore.js
index 2aa216835..1688e42fa 100644
--- a/underscore.js
+++ b/underscore.js
@@ -55,7 +55,7 @@
     module.exports = _;
     _._ = _;
   } else {
-    root._ = _;
+    root['_'] = _;
   }
 
   // Current version.