The invention relates to a fastener (10) for attaching together workpieces (50a, 50b) having aligned holes therethrough, the fastener (10) comprising a shank portion (11) and a head portion (13) provided at one end of the shank portion (11), the diameter of the shank portion (11) and/or of the head portion (13) being selected such that the fastener (10) can be installed in the aligned holes in close tolerance. The fastener (10) further comprises an oversizing structure (20), said oversizing structure (20) being firmly bonded to at least a part of the shank portion (11) and/or the head portion (13) in order to oversize at least the part of the shank portion (11) and/or the head portion (13) such as to allow the fastener (10) to be installed in aligned holes (60a, 60b) having a diameter larger than that required for the fastener (10) without the oversizing structure (20).