A drug delivery device for dispensing of a dose of a medicinal product, comprising a holder (14) for a product-containing cartridge (16), the cartridge (16) having a piston (18) slidably arranged therein in an axial direction, a piston rod (12) to be operably engaged with the cartridges piston (18) for dispensing of a dose of the medicinal product, and at least one spacer (20) being selected according to a relative distance between piston (18) and piston rod (12) and being disposed between the piston rod (12) and the piston (18) for eliminating axial clearance between piston (18) and piston rod (12).
