Index: modules/user/user.admin.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/user/user.admin.inc,v
retrieving revision 1.56
diff -u -9 -p -r1.56 user.admin.inc
--- modules/user/user.admin.inc	4 Jun 2009 20:09:29 -0000	1.56
+++ modules/user/user.admin.inc	6 Jun 2009 13:29:20 -0000
@@ -254,19 +254,20 @@ function user_admin_settings() {
   // Administrative role option.
   $form['admin_role'] = array(
     '#type' => 'fieldset',
     '#title' => t('Administrator role'),
   );
 
   // Do not allow users to set the anonymous or authenticated user roles as the
   // administrator role.
   $roles = user_roles();
-  $roles = array_slice($roles, 2, NULL, TRUE);
+  unset($roles[DRUPAL_ANONYMOUS_RID]);
+  unset($roles[DRUPAL_AUTHENTICATED_RID]);
   $roles[0] = t('disabled');
 
   $form['admin_role']['user_admin_role'] = array(
     '#type' => 'select',
     '#title' => t('Administrator role'),
     '#default_value' => variable_get('user_admin_role', 0),
     '#options' => $roles,
     '#description' => t('This role will be automatically assigned new permissions whenever a module is enabled. Changing this setting will not affect existing permissions.'),
   );