Method for stake-fastening an accessory (4) into a plastic fuel tank, whereby: the accessory (4) is equipped with at least one orifice (5) which passes right through the accessory (4); at least some of the plastic of which the wall of the tank (1) is made is melted; and some of the molten plastic is forced through the orifice (5) of the accessory without becoming detached from the remainder of the molten plastic; the protruding molten plastic is given an appropriate shape (8) to obtain a self-formed plastic rivet, and is left to solidify; the size and shape of the orifice (5) and/or of the solidified plastic (8) being such that the accessory (4) is mechanically fastened to the tank by at least some of the solidified plastic (8), the stake-fastening of the accessory (4) occurring at the time of manufacture of the tank (1) through the moulding of a split or at least two-part parison.