A turbocharger, having a turbine for expanding a first medium, having a compressor for compressing a second medium utilising energy extracted from the turbine during the expansion of the first medium, wherein the turbine comprises a turbine housing and a turbine rotor, wherein the compressor comprises a compressor housing and a compressor rotor coupled to the turbine rotor via a shaft, wherein the turbine housing and the compressor housing are each connected to a bearing housing arranged between the same, in which the shaft is mounted, wherein the turbine housing and the bearing housing are connected to one another via a fastening device in such a manner that the fastening device is mounted to a flange of the turbine housing with a first portion and with a second portion overlaps a flange of the bearing housing at least in portions, wherein between the flange of the turbine housing and the flange of the bearing housing at least one flange of a nozzle ring is clamped, and wherein between the flange of the turbine housing and the flange of the nozzle ring an axial sealing region between axial sealing faces (14, 15) of these flanges (6, 11) lying against one another is formed, characterised in that on the axial sealing face of the flange of the nozzle ring and/or on the axial sealing face of the flange of the turbine housing, a projection each is formed which engages in a recess in the respective other axial sealing face (14, 15), wherein the projection and the recess form a labyrinth seal, wherein upon different thermal expansion of turbine inflow housing, nozzle ring and bearing housing the projection is pressed into the groove and reinforces the sealing effect in the axial sealing region. having a turbine for expanding a first medium, having a compressor for compressing a second medium utilising energy extracted from the turbine during the expansion of the first medium, wherein the turbine comprises a turbine housing and a turbine rotor, wherein the compressor comprises a compressor housing and a compressor rotor coupled to the turbine rotor via a shaft, wherein the turbine housing and the compressor housing are each connected to a bearing housing arranged between the same, in which the shaft is mounted, wherein the turbine housing and the bearing housing are connected to one another via a fastening device in such a manner that the fastening device is mounted to a flange of the turbine housing with a first portion and with a second portion overlaps a flange of the bearing housing at least in portions, wherein between the flange of the turbine housing and the flange of the bearing housing at least one flange of a nozzle ring is clamped, and wherein between the flange of the turbine housing and the flange of the nozzle ring an axial sealing region between axial sealing faces (14, 15) of these flanges (6, 11) lying against one another is formed, characterised in that on the axial sealing face of the flange of the nozzle ring and/or on the axial sealing face of the flange of the turbine housing, a projection each is formed which engages in a recess in the respective other axial sealing face (14, 15), wherein the projection and the recess form a labyrinth seal, wherein upon different thermal expansion of turbine inflow housing, nozzle ring and bearing housing the projection is pressed into the groove and reinforces the sealing effect in the axial sealing region.