MIME::Parser Purge Does Not Remove Directories

[afrinspray]

I'm using MIME:arser with the following options:
$parser = new MIME:arser;
$parser->output_under("/tmp");
$parser->output_prefix("msg");
$parser->decode_headers(0);
$parser->extract_nested_messages(0);
$parser->extract_uuencode(1);
$parser->ignore_errors(1);

And after I'm done with the parser, I invoke:
$parser->filer->purge();

But it doesn't remove the 'msg' directory from /tmp that it created
(titled something like msg-11049...).

Any help would be greatly appreciated.

Mike