A pyrotechnic igniter includes at least one pyrotechnic material designed to be ignited by a heating element, a case enclosing the at least one pyrotechnic material, and a plastic overmoulding of the case, forming a fixation interface of the igniter and designed to be inserted into a fixation orifice of a support up to an inserted position. The fixation interface of the plastic overmoulding includes at least one deformable part designed to elastically deform during passage into the fixation orifice and assume during an elastic return a blocking position against the support when the igniter is in the inserted position in order to prevent any withdrawal of the igniter.