The invention relates to an adjustable fastening device including at least one sleeve nut having an aperture with a first internal thread and a through-bore following the same along the longitudinal axis of the fastening device (1), and also including a drum screw with an external thread and a tensioning screw lead-through, in the case of which the drum screw engages, by way of the external thread, in the first internal thread of the sleeve nut. According to the invention, the sleeve nut has on the free peripheral region, which forms the opening of the aperture, a rivet-collar portion and a central sleeve portion, which projects into the aperture in the direction of the rivet-collar portion, wherein the tensioning-screw lead-through of the drum screw is designed to accommodate the central sleeve portion at least in part.