The invention relates to a seal of a fastening element (1), comprising the fastening element (1) and a washer (2) therefor, wherein the fastening element (1) and the washer (2) are arranged coaxially and axially adjacent to one another, wherein the washer (2) has a sealing bead (3) made of a rubber-elastic sealing material on the outer circumference, and wherein the sealing bead (3) contacts the underside (4) of the fastening element (1) in a sealing manner during the correct use of the seal. The fastening element (1) has a flange (5) on the side axially facing the washer (2), having an underside (6) axially facing the washer (2), wherein the washer (2) has a top side axially facing the flange (5), wherein the underside (6) of the flange (5) and the top side (7) of the washer (2) abut in a sealing manner during the correct use of the seal, wherein the underside (6) of the flange (5) and the top side (7) of the washer (2) are substantially congruent, and wherein the sealing bead (3) abuts the outer circumferential boundary (8) of the underside (6) of the flange (5) in a sealing manner.