The invention pertains to an illumination device (1) for a motor vehicle headlight, wherein said illumination device (1) comprises the following: an optical assembly (100), which comprises at least one light source and a cooling element (110) that has at least three first openings (111), a supporting frame (200), which has at least three second openings (210) that are assigned to the at least three first openings (111), and an adapter component (300), which has a number of dowel pins (310) that corresponds to the number of first openings (111), with the dowel pins (310) respectively having a threaded bore (311) and respectively being inserted into a first opening (111), wherein a screw unit (400) with a mating thread (410) corresponding to the threaded bore (311) is provided for each dowel pin (310), wherein said screw unit (400) penetrates the supporting frame (200) through a second opening (210) of the supporting frame (200) and is screwed into the respective dowel pin (310), and wherein the dowel pins (310) are designed for expanding when a screw unit (400) is screwed into the dowel pin (310) such that the dowel pins (310) inserted into the first openings (111) of the cooling element (110) are frictionally connected to the cooling element (110).