A lighting device for a motor vehicle headlamp is described. The device includes a reflector for focusing light emitted by a light source. At the rear end of the reflector is an opening to receive at least a part of the light source, and a reflector neck that surrounds the opening and to which the light source is fastened in a defined position relative to a reflective surface of the reflector. A plurality of locking members are formed on the reflector which in the course of a rotary movement of the light source about the optical axis of the reflector or about an axis parallel thereto when the light source has been at least partly inserted in the reflector neck, engage in corresponding perforations formed in the fight source.