Abstract: Improved safety device for installation on door jambs in hotels, motels and the like to prevent the use of shim-type devices for unauthorized entry into guest rooms, wherein the device comprises a right angled strip of metal, to be secured to the door jamb opposite the free end of the door when the door is in the closed position, the device having a portion adapted to lap against the outer side of the door, so as to provide maximum resistance to insertion of a shim or similar article between door and lapped portion, thus preventing penetration far enough to disengage the latch bolt from the striker plate aperture in which it is engaged in the normal, locked position.