The present disclosure concerns a counting mechanism for a drug delivery device, comprising a first counting member comprising an interaction element, a second counting member comprising engagement elements that are configured to engage with the interaction element of the first counting member, and a separating member, wherein the first counting member is moveable relative to the separating member between a first and a second relative position, and the separating member is configured to prevent an engagement of the interaction element with the engagement elements when the first counting member is in the second relative position with respect to the separating member. Further, the present disclosure concerns a drug delivery device comprising said counting mechanism.