diff -urp --strip-trailing-cr ../drupal-6.x-dev/install.php ./install.php
--- ../drupal-6.x-dev/install.php	2007-12-20 09:26:42.000000000 +0100
+++ ./install.php	2007-12-23 13:23:52.000000000 +0100
@@ -540,7 +540,7 @@ function install_select_locale($profilen
     }
 
     foreach ($locales as $locale) {
-      if ($_POST['locale'] == $locale->name) {
+      if (isset($_POST['locale']) && $_POST['locale'] == $locale->name) {
         return $locale->name;
       }
     }
@@ -558,6 +558,7 @@ function install_select_locale($profilen
  */
 function install_select_locale_form(&$form_state, $locales) {
   include_once './includes/locale.inc';
+  include_once './modules/locale/locale.module';
   $languages = _locale_get_predefined_list();
   foreach ($locales as $locale) {
     // Try to use verbose locale name