diff --git a/src/peg.js b/src/peg.js
index 21dc108..7958148 100644
--- a/src/peg.js
+++ b/src/peg.js
@@ -1,4 +1,6 @@
-(function(global, undefined) {
+(function(global) {
+
+var undefined;
 
 var PEG = {
   /*