Warning: Parameter 1 to creeper_admin_settings() expected to be a reference, value given in drupal_retrieve_form()

On the config page I receive this error instead of the config form;
Warning: Parameter 1 to creeper_admin_settings() expected to be a reference, value given in drupal_retrieve_form()

The error comes from creeper.admin.inc, line 2:

function creeper_admin_settings(&$form_state) {

in D7 $form_state is the second attribute, like this it works fine:

function creeper_admin_settings($form, &$form_state) {