A rivet machine is provided. The rivet machine employs a die including a die body that has an inner wall with a pair of retaining ribs or projections extending inwardly therefrom. In use, the rivet pushes a slug from a workpiece within which it is mounted and into an opening of the die. The projections engage and retain the slug within the inner wall. According to further aspects, the pair of retaining ribs are diametrically opposed around the inner wall. Each of the retaining ribs has two converging surfaces that form an angle of between 90 and 150 degrees. In yet another aspect, the projections can be discontinuous such that a first retaining rib is longitudinally offset on the inner wall from a second retaining rib.