How to get 404 error when file is not available?

[itman]

Hi!
When a file is deleted or expired and public user is trying to open it using the link that previously pointed directly to that file (domain.com/.../category_name?download=999:filename), PD throws login screen with access error instead of 404 error. Also search engines complain about redirecting.
It there a setting or workaround to get 404 error in case the file is no longer available?