A
dose setting-correcting mechanism for a
pen injector comprising a rotatable
coupling sleeve having a proximal end (1a, 101a) and a distal end (1b, 101b), a rotatable
ratchet sleeve (2, 102) surrounding the
coupling sleeve (1, 101) and splined therewith axially, a reset nut (3, 103), a setting ring (6, 106), a
crown gear (4, 104), said elements arranged around longitudinal axis A. For setting a
dose, rotation of the
coupling sleeve (1, 101) in a first direction causes rotation of the
ratchet sleeve (2, 102). For
dose correcting, the coupling sleeve (1, 101) is firstly rotated with respect to the
ratchet sleeve (2, 102) and the reset nut (3, 103) is rotated along with the coupling sleeve (1, 101), wherein rotation of the reset nut (3, 103) causes sliding movement between the teeth of the reset nut and the teeth of the crown, and as a result, the axial movement of the
crown gear (4, 104) and decoupling the
crown gear (4, 104) from the setting ring (6, 106) so that the setting ring (6, 106) rotates to correct the dose. A
pen injector comprising such a mechanism.