The present disclosure provides for a drive assembly for a drug delivery device. The drive assembly comprises a housing (4)； a piston rod having a longitudinal axis, a distal end and a proximal end and being axially movable in a distal direction relative to the housing and a mid-body (20) axially fixed inside of the housing (4) and coupled to the piston rod. The mid-body (20) comprises at least one metal ratchet arm (81 ) configured to prevent the piston rod from moving in the proximal direction. Moreover, a drug delivery device with such a drive assembly is presented.
