diff --git a/CHANGELOG b/CHANGELOG
index 171e4fa..dd42f09 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,6 +1,6 @@
 *SVN*
 
-* Fix Function#argumentNames for Opera [Thomas Fuchs]
+* Fix Function#argumentNames for Opera and IE.  [Thomas Fuchs]
 
 * Add Object.isString, Object.isNumber, and Object.isUndefined, and clean up the source to make use of Object.isXXX where possible.  [sam]
 
diff --git a/src/base.js b/src/base.js
index 853c23d..b2fb118 100644
--- a/src/base.js
+++ b/src/base.js
@@ -154,7 +154,7 @@ Object.extend(Object, {
 
 Object.extend(Function.prototype, {
   argumentNames: function() {
-    var names = this.toString().match(/^\s*function\s*\((.*?)\)/)[1].split(",").invoke("strip");
+    var names = this.toString().match(/^[\s\(]*function\s*\((.*?)\)/)[1].split(",").invoke("strip");
     return names.length == 1 && !names[0] ? [] : names;
   },