A method for assembling a drug delivery device, comprising the steps of: - providing a cartridge containing a drug and a piston being retained within the cartridge, wherein the distal portion of the cartridge comprises an outwardly directed shoulder portion, - providing a cartridge holder having a proximal end and a distal end, wherein the distal portion of the cartridge holder comprises an inwardly directed flange portion, the shoulder portion of the cartridge being of suitable dimension to abut the flange portion, - providing a housing and a piston rod being retained in the housing, the piston rod being operable to displace the piston with respect to the cartridge, - after inserting the cartridge into the cartridge holder, securing the cartridge holder to the housing, such that the piston is arranged at a distance from the piston rod, - characterized by securing the cartridge in the cartridge holder according to the following steps: • axially displacing the cartridge in the proximal direction with respect to the cartridge holder from a distal initial position to a proximal end position such that the piston is displaced towards the piston rod such that the gap between the piston and the piston rod is minimized or closed, • subsequently, securing the cartridge in the proximal end position against displacement in the distal direction with respect to the cartridge holder by means of an adjusting member in the form of a needle insert (25, 34), wherein the adjusting member is arranged in the distal portion of the cartridge holder preventing an abutment of the shoulder portion of the cartridge and the flange portion of the cartridge holder. - providing a cartridge containing a drug and a piston being retained within the cartridge, wherein the distal portion of the cartridge comprises an outwardly directed shoulder portion, - providing a cartridge holder having a proximal end and a distal end, wherein the distal portion of the cartridge holder comprises an inwardly directed flange portion, the shoulder portion of the cartridge being of suitable dimension to abut the flange portion, - providing a housing and a piston rod being retained in the housing, the piston rod being operable to displace the piston with respect to the cartridge, - after inserting the cartridge into the cartridge holder, securing the cartridge holder to the housing, such that the piston is arranged at a distance from the piston rod, - characterized by securing the cartridge in the cartridge holder according to the following steps: • axially displacing the cartridge in the proximal direction with respect to the cartridge holder from a distal initial position to a proximal end position such that the piston is displaced towards the piston rod such that the gap between the piston and the piston rod is minimized or closed, • subsequently, securing the cartridge in the proximal end position against displacement in the distal direction with respect to the cartridge holder by means of an adjusting member in the form of a needle insert (25, 34), wherein the adjusting member is arranged in the distal portion of the cartridge holder preventing an abutment of the shoulder portion of the cartridge and the flange portion of the cartridge holder. • axially displacing the cartridge in the proximal direction with respect to the cartridge holder from a distal initial position to a proximal end position such that the piston is displaced towards the piston rod such that the gap between the piston and the piston rod is minimized or closed, • subsequently, securing the cartridge in the proximal end position against displacement in the distal direction with respect to the cartridge holder by means of an adjusting member in the form of a needle insert (25, 34), wherein the adjusting member is arranged in the distal portion of the cartridge holder preventing an abutment of the shoulder portion of the cartridge and the flange portion of the cartridge holder.