A gas turbine includes an insert element for fastening to a ring segment body of a turbine of the gas turbine. The ring segment body has a recess on a hot gas side. The insert element is designed to cover the recess. The insert element includes a cover plate, which has a concavely shaped front side and a back side, and at least one foot arranged on the back side for positioning on the ring segment body. A mounting method includes mounting the insert element where the insert element is fixed to a recess of a ring segment body of a turbine of a gas turbine.