[support] Limiting path arguments to hook_menu

I have (in D7)

function foo_menu() { $items = array(); $items['foo'] = array( 'title' => 'Foo', 'page arguments' => array("foo"), 'page callback' => 'super_page', 'access arguments' => array('access content'), 'file' => 'pages/super_page.inc', 'type' => MENU_CALLBACK, ); return $items }

At the moment, /foo works as a path. However, so does /foo/bar etc, which calls the super_page callback. In reality I'd like this to 404. Is there something obvious I'm missing or do I need to count the number of arguments passed to things like super_page and return drupal_not_found()?