Abstract: A wind power machine including a mast that is articulated so as to adopt an upright position above a foundation anchored into the ground and a folded-up position close to the ground. The mast includes substantially straight parts articulated together so as to pivot to bring the mast into the upright position or into the folded-up position. The wind power machine further includes a locking device placed at least one of the articulations between two of these parts to lock the mast in the upright position. The locking device includes: a radially movable clamping ring, placed at the end of one of the two parts of the articulation inside the mast; and an actuation mechanism capable of moving the clamping ring radially so as to produce an intimate male/female-type connection between the two parts of the articulation.