Redirect Caching Doesn't Work

By the looks of it, the cause is line 959 of redirect.module:
  if (!variable_get('redirect_page_cache', 0) || !variable_get('cache', 0) || !drupal_page_is_cacheable() || empty($redirect['cache'])) {

Given $redirect is an object, this change gets it working:
  if (!variable_get('redirect_page_cache', 0) || !variable_get('cache', 0) || !drupal_page_is_cacheable() || empty($redirect->cache)) {

P.S. Great module!! ;)