A mechanism for a drug delivery device, having a first and a second state, including an engagement preventing member, and a blocking member having a blocking feature and an engagement element which is engagable with the blocking member. The blocking member is configured to engage with the engagement element in a non-linear movement, thereby moving the blocking feature is moved from a first position to a second position in an arc shaped movement. In the first state of the mechanism, the engagement preventing member is configured to prevent an engagement of the blocking member with the engagement element by covering the engagement element, and wherein, in the second state of the mechanism, the engagement element is free from the engagement preventing member such that the blocking member is enabled to engage with the engagement element.
