A device for fastening molded or extruded plastics parts, more particularly to an automotive body, by positive locking, comprising a base section joinable to said plastics part to be fastened, and a retaining section adjoining said base section in a fastening direction, said retaining section protruding beyond said base section perpendicular to said fastening direction for forming a contact base, said base section and said retaining section being made of an elastically deformable material, and at least said retaining section comprising a cavity which includes at least one elastically deformable partition being arranged in said cavity, which is configured as a through-hole extending in a normal direction perpendicular to said fastening direction, said partition extending in a plane oriented perpendicular to said normal direction.