A motor vehicle lamp with a device for at least partially fastening the motor vehicle lamp in an installation opening of a body of a vehicle, wherein means for fixing at least one threaded bolt are arranged at the motor vehicle lamp, wherein the device comprises a hollow screw with an external thread and a central opening, which extends coaxially to the longitudinal axis of the hollow screw, a threaded bolt, which is fixed at the motor vehicle lamp, with a first thread section extending through the central opening, as well as a sleeve-shaped clamping unit, which is arranged in the central opening over the first thread section coaxially between the hollow screw and the threaded bolt, wherein: - the hollow screw has a collar arranged on one side of the external thread and projecting radially from the hollow screw, which collar in a mounted state of the device faces toward the motor vehicle lamp, - the clamping unit is arranged in the central opening to be rotatable about the longitudinal axis of the hollow screw, - the clamping unit is arranged form-lockingly in axial direction in parallel to the longitudinal axis of the hollow screw, - the clamping unit has a continuous, axial opening extending coaxially to the longitudinal axis of the hollow screw, the inside diameter of which axial opening is smaller than the outside diameter of the first thread section of the threaded bolt, and - the clamping unit comprises a shoulder, which has a design such that it can be brought into engagement with a tool in order to rotate the clamping unit in relation to the hollow screw, characterised in that: - at least one stop groove is arranged in the collar of the hollow screw, - at least one stop is arranged corresponding with the at least one stop groove of the collar of the hollow screw, which stop in a mounted state of the device engages into the at least one stop groove for the purpose of torque support, - the collar, at its side averted from the external thread, comprises a hollow cylinder extending coaxially to the longitudinal axis, in the shell surface of which hollow cylinder the at least one stop groove extends in parallel to the longitudinal axis of the hollow screw, and, - when the hollow screw is rotated about its longitudinal axis, the end face of the shell surface of the hollow cylinder, which end face is averted from the collar, has a thread lead from stop groove to stop groove such that, of two edges (27, 28) of the shell surface bounding a stop groove, the edge that leads in the direction of screwing-in the hollow screw onto the threaded bolt has a smaller distance from the collar, as seen axially along the longitudinal axis of the hollow screw, than the edge that trails in the direction of screwing-in the hollow screw onto the threaded bolt. - the hollow screw has a collar arranged on one side of the external thread and projecting radially from the hollow screw, which collar in a mounted state of the device faces toward the motor vehicle lamp, - the clamping unit is arranged in the central opening to be rotatable about the longitudinal axis of the hollow screw, - the clamping unit is arranged form-lockingly in axial direction in parallel to the longitudinal axis of the hollow screw, - the clamping unit has a continuous, axial opening extending coaxially to the longitudinal axis of the hollow screw, the inside diameter of which axial opening is smaller than the outside diameter of the first thread section of the threaded bolt, and - the clamping unit comprises a shoulder, which has a design such that it can be brought into engagement with a tool in order to rotate the clamping unit in relation to the hollow screw, - at least one stop groove is arranged in the collar of the hollow screw, - at least one stop is arranged corresponding with the at least one stop groove of the collar of the hollow screw, which stop in a mounted state of the device engages into the at least one stop groove for the purpose of torque support, - the collar, at its side averted from the external thread, comprises a hollow cylinder extending coaxially to the longitudinal axis, in the shell surface of which hollow cylinder the at least one stop groove extends in parallel to the longitudinal axis of the hollow screw, and, - when the hollow screw is rotated about its longitudinal axis, the end face of the shell surface of the hollow cylinder, which end face is averted from the collar, has a thread lead from stop groove to stop groove such that, of two edges (27, 28) of the shell surface bounding a stop groove, the edge that leads in the direction of screwing-in the hollow screw onto the threaded bolt has a smaller distance from the collar, as seen axially along the longitudinal axis of the hollow screw, than the edge that trails in the direction of screwing-in the hollow screw onto the threaded bolt.