diff --git a/CHANGELOG b/CHANGELOG
index 08dc3d7..171e4fa 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Fix Function#argumentNames for Opera [Thomas Fuchs]
+
 * Add Object.isString, Object.isNumber, and Object.isUndefined, and clean up the source to make use of Object.isXXX where possible.  [sam]
 
 * Add the document.viewport object for querying dimensions and scroll offsets of the browser viewport.  [Andrew Dupont, Thomas Fuchs, sam]
diff --git a/src/base.js b/src/base.js
index 07ac8d9..853c23d 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(/^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;
   },