i18n breaks Quickfile

The use of the Internationalization module (i18n) breaks quickfile.

The behavior is that the page from the Thank You URL is displayed but there is no text and link "Download your quickfile" on the page.

I suspect this is because with the i18n module enabled, a change is introduced which adds the ISO two letter language code to all URLs.

Here are two sample URLs sent by the Quickfile email feature. The second, which was generated with the i18n module enabled which contains an additional "en/" doesn't work.
http://example.com/purchase_thankyou?txnid=4HH65116R8248392H&nid=5&metho...
http://example.com/en/purchase_thankyou?txnid=858575959M015111T&nid=5&me...

Even if I change the Quickfile configuration for IPN URL to include the language "www.example.com/en/quickfile_paypal/ipn" it does not work, and even if it did work it would be a solution for only one language, not the multiple languages that i18n is meant to support.