Drug delivery device adapted to receive a cartridge, comprising a piston driver adapted to expel an amount of drug from a received cartridge, and a base member adapted to engage a cartridge and position the cartridge relative to the piston driver, the base member comprising a main portion with a central passage, a portion of the piston driver being arranged axially displaceable through the passage, the piston driver distal end being arranged distally of the central passage, and flexible centring means adapted to receive the proximal end of a cartridge and centre it relative to the central opening and thereby to the piston driver.
