diff --git a/underscore.js b/underscore.js
index f09221580..47a330b06 100644
--- a/underscore.js
+++ b/underscore.js
@@ -54,7 +54,7 @@
   if (typeof module !== 'undefined' && module.exports) {
     module.exports = _;
     _._ = _;
-  } else if (exports !== 'undefined') {
+  } else if (typeof exports !== 'undefined' && exports) {
     exports._ = _;
   } else {
     // Exported as a string, for Closure Compiler "advanced" mode.