Described is an autoinjector (1) comprising a case (2) adapted to hold a medicament container having a needle (4) and the case (2) including a rib (2.6), a needle shroud (7) slidably disposed in the case (2) and translatable between an extended position (EP) relative to the case (2) in which the needle (4) is covered and a retracted position (RP) relative to the case (2) in which the needle (4) is exposed, and a plunger (10) slidably disposed in the case (2). The plunger (10) includes a plunger boss (10.1) adapted to abut the rib (2.6) and the needle shroud (7) when the needle shroud (7) is in the extended position (EP) and disengage the rib (2.6) when the needle shroud (7) is in the retracted position (RP) to allow the plunger (10) to translate axially relative to the case (2).
