diff --git a/wp-includes/functions-compat.php b/wp-includes/functions-compat.php
index 7a17b0aa6..768dd4e86 100644
--- a/wp-includes/functions-compat.php
+++ b/wp-includes/functions-compat.php
@@ -47,4 +47,46 @@ function printr($var, $do_not_echo = false) {
 	return $code;
 }
 
+if (!defined('CASE_LOWER')) {
+    define('CASE_LOWER', 0);
+}
+
+if (!defined('CASE_UPPER')) {
+    define('CASE_UPPER', 1);
+}
+
+
+/**
+ * Replace array_change_key_case()
+ *
+ * @category    PHP
+ * @package     PHP_Compat
+ * @link        http://php.net/function.array_change_key_case
+ * @author      Stephan Schmidt <schst@php.net>
+ * @author      Aidan Lister <aidan@php.net>
+ * @version     $Revision$
+ * @since       PHP 4.2.0
+ * @require     PHP 4.0.0 (user_error)
+ */
+if (!function_exists('array_change_key_case')) {
+    function array_change_key_case($input, $case = CASE_LOWER)
+    {
+        if (!is_array($input)) {
+            user_error('array_change_key_case(): The argument should be an array',
+                E_USER_WARNING);
+            return false;
+        }
+
+        $output   = array ();
+        $keys     = array_keys($input);
+        $casefunc = ($case == CASE_LOWER) ? 'strtolower' : 'strtoupper';
+
+        foreach ($keys as $key) {
+            $output[$casefunc($key)] = $input[$key];
+        }
+
+        return $output;
+    }
+}
+
 ?>
\ No newline at end of file