The invention relates to a lock for an anti-theft device for a motor vehicle steering column comprising a rotor (5), a stator head (4), a lug (13) and a complementary profile (14), one supported by the rotor (5) and the other by the stator head (4), the complementary profile (14) being shaped such that the engagement of same with the lug (13) blocks the rotation of the rotor (5) in a predetermined direction of rotation (AR) from a predetermined angular position (PIA) and allows the rotation of the rotor (5) by pushing the rotor (5) in beforehand. The complementary profile (14) is also shaped so that the engagement of the complementary profile (14) and the lug (13) guides the assembly of the rotor (5) in the stator head (4) according to a push-rotated assembly in which the rotor (5) is axially retained in the stator head (4).