An assembly for a medication delivery device comprising - a body, - a piston rod adapted and arranged to be rotated with respect to the body in a dose setting state of the assembly for setting a dose of a medication and to be axially moved in a distal direction with respect to the body in a dose delivering state of the assembly for delivering the set dose of the medication, and - a setting nut secured against rotational movement with respect to the body, but enabled for axial movement with respect to the body, and further helically coupled with the piston rod, wherein the setting nut is adapted and arranged to axially travel in the proximal direction with respect to the body for setting a dose of a medication due to a helical movement of the setting nut with respect to the piston rod when the piston rod is rotated with respect to the body in the dose setting state of the assembly, and wherein the setting nut is adapted and arranged to axially travel in the distal direction with respect to the body for delivering the set dose of the medication when the piston rod is axially moved in the distal direction with respect to the body in the dose delivering state of the assembly, characterized in that the piston rod and the body comprise anti-rotation features engaging with each other in the dose delivering state for preventing a rotational movement of the piston rod in the dose delivering state, such that the setting nut is secured against relative movement with respect to the piston rod when the piston rod is axially moved in the distal direction with respect to the body in the dose delivering state. - a body, - a piston rod adapted and arranged to be rotated with respect to the body in a dose setting state of the assembly for setting a dose of a medication and to be axially moved in a distal direction with respect to the body in a dose delivering state of the assembly for delivering the set dose of the medication, and - a setting nut secured against rotational movement with respect to the body, but enabled for axial movement with respect to the body, and further helically coupled with the piston rod, wherein the setting nut is adapted and arranged to axially travel in the proximal direction with respect to the body for setting a dose of a medication due to a helical movement of the setting nut with respect to the piston rod when the piston rod is rotated with respect to the body in the dose setting state of the assembly, and wherein the setting nut is adapted and arranged to axially travel in the distal direction with respect to the body for delivering the set dose of the medication when the piston rod is axially moved in the distal direction with respect to the body in the dose delivering state of the assembly, characterized in that the piston rod and the body comprise anti-rotation features engaging with each other in the dose delivering state for preventing a rotational movement of the piston rod in the dose delivering state, such that the setting nut is secured against relative movement with respect to the piston rod when the piston rod is axially moved in the distal direction with respect to the body in the dose delivering state. wherein the setting nut is adapted and arranged to axially travel in the proximal direction with respect to the body for setting a dose of a medication due to a helical movement of the setting nut with respect to the piston rod when the piston rod is rotated with respect to the body in the dose setting state of the assembly, and wherein the setting nut is adapted and arranged to axially travel in the distal direction with respect to the body for delivering the set dose of the medication when the piston rod is axially moved in the distal direction with respect to the body in the dose delivering state of the assembly, characterized in that the piston rod and the body comprise anti-rotation features engaging with each other in the dose delivering state for preventing a rotational movement of the piston rod in the dose delivering state, such that the setting nut is secured against relative movement with respect to the piston rod when the piston rod is axially moved in the distal direction with respect to the body in the dose delivering state.