A cartridge assembly (300) for a drug delivery device is proposed, comprising:a cartridge holder (301), a cartridge (302) containing a drug, and a fixing member (303), wherein the cartridge holder comprises an interior cartridge holding section, the cartridge being arranged in the cartridge holding section, wherein the fixing member is axially secured to the cartridge holder and secures the cartridge permanently in the cartridge holder. Further, a method for assembling the cartridge assembly is disclosed.
