The invention proposes a lighting headlamp for a motor vehicle, comprising a light source, a reflector of the elliptical type, a first focus of which is arranged in the vicinity of the source and a second focus of which is arranged in the vicinity of the focal plane of a convergent lens, and a movable mask which is mounted so as to pivot, with respect to a fixed mounting, about an overall transverse axis, and which is capable of occupying an angular occultation position, in which it is arranged substantially vertically in the vicinity of the focal plane of the lens so as to form a cutoff in the light beam produced by the headlamp, and a retracted angular position, a spring forcing the movable mask into its occultation position, wherein it also comprises at least one locking means acting between the mounting and the mask in order to hold the mask in its occultation position.