Abstract: A cylindrical lever handle lock mounted in a door panel having a transverse bore therethrough is secured against rotation due to torque applied to the lever handles. The lock mechanism includes a lock chassis having a pair of chassis support members each having a pair of slots on their peripheries. A pair of support plates having inwardly extending tongue members slide into the support plate openings. The support plates are of a diameter greater than the bore and have openings in the periphery of each which corresponds with a hole drilled in the door panel outside of the bore. Door handle roses are secured over the support plates by through-bolts which pass through the support plate peripheral openings and the drilled door holes. Threaded bushings are also utilized to tighten the support plates on either side of the bore. Additional tabs and screws may be used to non-rotatably secure the support plates to the door panel.