diff --git a/src/showdown.js b/src/showdown.js
index b488bad..4234bb7 100644
--- a/src/showdown.js
+++ b/src/showdown.js
@@ -116,8 +116,7 @@ var g_output_modifiers = [];
 //
 // Automatic Extension Loading (node only):
 //
-
-if (typeof module !== 'undefind' && typeof exports !== 'undefined' && typeof require !== 'undefind') {
+if (typeof window === 'undefined' && typeof module !== 'undefind' && typeof exports !== 'undefined' && typeof require !== 'undefind') {
 	var fs = require('fs');
 
 	if (fs) {