An exhaust-gas turbocharger (1) having a shaft (2), a turbine wheel (5), which is fastened to the shaft (2), and a heat throttle (8) between the shaft (2) and the turbine wheel. An end face (3) of the shaft (2) is provided with a protrusion (4), with an outside diameter (A4) which is smaller than the outside diameter (A2) of the shaft (2). The turbine wheel (5) has a hollow receiving portion (7), which is formed integrally on the wheel rear side (6) and the inside diameter (I7) corresponds to the outside diameter (A4) of the protrusion (4) and the outside diameter (A7) corresponds to the outside diameter (A2) of the shaft (2). The protrusion (4) engages into the receiving portion (7). The heat throttle (8) is formed by a cavity (8A, 8B), which has an outside diameter (A8) which is smaller than the outside diameter (A4) of the protrusion (4) and extends from the protrusion (4) into the receiving portion (7).