Abstract: A combine harvester includes a grain tank with an upper opening and a foldable attachment disposed on the upper opening. The attachment has two opposing, one-piece, flat attachment parts and two opposing, multiple-component, flat attachment parts. The attachment parts are swivellably disposed on the upper edge of the upper opening of the grain tank, are swivellably connected to one another and, in lying-flat, closed positions, form a cover. The cover at least partially closes the opening. In erected filling positions, the attachment parts increase the volume of the grain tank.