An auto-injector comprising a body (1) and an actuator sleeve (10) that can be moved relative to said body (1), said actuator sleeve (10) being in a first projected position before actuation of the auto-injector and in a second projected position after actuation of the auto-injector, one of said actuator sleeve (10) and said body (1) comprising a flexible tab (110) capable of deforming laterally relative to said actuator sleeve (10) and/or relative to said body (1) when said actuator sleeve (10) is moved from the first projected position of same to the actuation position of same, then from the actuation position of same back to the second projected position of same, the other of said actuation sleeve (10) and said body (1) comprising an initial area (102) that engages with said flexible tab (110) in said first projected position, an intermediate area (105) that engages with said flexible tab (110) in said actuation position, and a final reception area (106) that engages with said flexible tab (110) in said second projected position, said final reception area (106) being offset at least laterally from said initial area (102), a deformable axial wall (1020) being capable of being elastically deformed to allow said flexible tab (110) to pass from said initial area (102) to said intermediate area (105), said deformable axial wall (1020), in the non-deformed position of same, then being capable of guiding said flexible tab from said intermediate area (105) to said final reception area (106).