CustomPress: Post-Type Search

I'm unable to restrict searches against custom post types to a single post type.

Searches performed on the back-end, regardless of which post type you're looking at, show results for everything.

Searches on the front end, even with a manually appended "&post_type=foo" query string, return results with everything.

Is there a problem with the plugin, or do I have to add a filter to my search template (using an untouched bp-default) ?