diff --git a/lib/index.js b/lib/index.js
index a435e59..f1411b3 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -99,14 +99,15 @@ Tree.prototype.set = function(key, value) {
     node.value = value;
     return this;
 };
+var _treeToString =  function() { return '[object Tree]'; };
+if(process && process.env  && process.env.NODE_ENV === 'development'){
+    _treeToString =  require('./toString') ;
+}
 
-var _treeToString = process.env.NODE_ENV === 'development' ?
-    require('./toString') :
-    function() { return '[object Tree]'; };
 
 /**
  * For debuggability
- * 
+ *
  * @returns {String}
  */
 Tree.prototype.toString = function() {