In a locking device for a door, window or the like, having a main lock box, at least one supplementary lock box, and at least one drive rod connecting the supplementary lock boxes to the main lock box, better resistance to break-ins is attained in that the supplementary lock box has a latch bolt that can be retracted freely into the latching position, wherein the latch bolt is displaceable by a spring and/or by a gear past the normal latching position into its locking position.