diff --git a/CHANGELOG b/CHANGELOG
index d61f9eb..c6222b6 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,8 @@
 *SVN*
 
+* Deprecate document.getElementsByClassName and Element#getElementsByClassName since native versions return a NodeList and we can only return an Array.  Please use $$ or Element#select instead.  [sam]
+  For more information see https://bugzilla.mozilla.org/show_bug.cgi?id=390411
+
 * Fix missing "var" in selector.js.  Closes #9761.  [Tobie Langel]
 
 * Date#toJSON now returns times in UTC for better compatibility with json.js.  Closes #9332.  [Tobie Langel]
diff --git a/src/deprecated.js b/src/deprecated.js
index b669303..59d91fe 100644
--- a/src/deprecated.js
+++ b/src/deprecated.js
@@ -113,6 +113,41 @@ var Position = {
 
 /*--------------------------------------------------------------------------*/
 
+if (!document.getElementsByClassName) document.getElementsByClassName = function(instanceMethods){
+  function iter(name) {
+    return name.blank() ? null : "[contains(concat(' ', @class, ' '), ' " + name + " ')]";
+  }
+
+  instanceMethods.getElementsByClassName = Prototype.BrowserFeatures.XPath ?
+  function(element, className) {
+    className = className.toString().strip();
+    var cond = /\s/.test(className) ? $w(className).map(iter).join('') : iter(className);
+    return cond ? document._getElementsByXPath('.//*' + cond, element) : [];
+  } : function(element, className) {
+    className = className.toString().strip();
+    var elements = [], classNames = (/\s/.test(className) ? $w(className) : null);
+    if (!classNames && !className) return elements;
+
+    var nodes = $(element).getElementsByTagName('*');
+    className = ' ' + className + ' ';
+
+    for (var i = 0, child, cn; child = nodes[i]; i++) {
+      if (child.className && (cn = ' ' + child.className + ' ') && (cn.include(className) ||
+          (classNames && classNames.all(function(name) {
+            return !name.toString().blank() && cn.include(' ' + name + ' ');
+          }))))
+        elements.push(Element.extend(child));
+    }
+    return elements;
+  };
+
+  return function(className, parentElement) {
+    return $(parentElement || document.body).getElementsByClassName(className);
+  };
+}(Element.Methods);
+
+/*--------------------------------------------------------------------------*/
+
 Element.ClassNames = Class.create();
 Element.ClassNames.prototype = {
   initialize: function(element) {
diff --git a/src/dom.js b/src/dom.js
index f9306c8..cdce566 100644
--- a/src/dom.js
+++ b/src/dom.js
@@ -633,39 +633,6 @@ Element.Methods = {
 
 Element.Methods.identify.counter = 1;
 
-if (!document.getElementsByClassName) document.getElementsByClassName = function(instanceMethods){
-  function iter(name) {
-    return name.blank() ? null : "[contains(concat(' ', @class, ' '), ' " + name + " ')]";
-  }
-
-  instanceMethods.getElementsByClassName = Prototype.BrowserFeatures.XPath ?
-  function(element, className) {
-    className = className.toString().strip();
-    var cond = /\s/.test(className) ? $w(className).map(iter).join('') : iter(className);
-    return cond ? document._getElementsByXPath('.//*' + cond, element) : [];
-  } : function(element, className) {
-    className = className.toString().strip();
-    var elements = [], classNames = (/\s/.test(className) ? $w(className) : null);
-    if (!classNames && !className) return elements;
-
-    var nodes = $(element).getElementsByTagName('*');
-    className = ' ' + className + ' ';
-
-    for (var i = 0, child, cn; child = nodes[i]; i++) {
-      if (child.className && (cn = ' ' + child.className + ' ') && (cn.include(className) ||
-          (classNames && classNames.all(function(name) {
-            return !name.toString().blank() && cn.include(' ' + name + ' ');
-          }))))
-        elements.push(Element.extend(child));
-    }
-    return elements;
-  };
-
-  return function(className, parentElement) {
-    return $(parentElement || document.body).getElementsByClassName(className);
-  };
-}(Element.Methods);
-
 Object.extend(Element.Methods, {
   getElementsBySelector: Element.Methods.select,
   childElements: Element.Methods.immediateDescendants