The invention relates to an autoinjector (1) comprising: a case (2) adapted to hold a medicament container having a needle (4)； a needle shroud (7) telescopically coupled to the case (2) and movable between a first extended position (FEP) 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) rotationally and slidably disposed in the case (2), the plunger (10) rotatable relative to the case (2) between a first rotational position in which the plunger (10) is engaged to the case (2) and a second rotational position in which the plunger (10) disengages the case (2), wherein the needle shroud (7) engages the plunger (10) to rotate the plunger (10) from the first rotational position to the second rotational position when the needle shroud (7) translates from the first extended position (FEP) to the retracted position (RP), the auto-injector (1) further comprising: a cap (11) removably coupled to the case (2), wherein the cap (11) includes at least one compliant case beam (11.6) adapted to releasably engage at least one aperture (2.16) in the case (2).
