Close the accordion door all the way. If you have a long closet with more than one door, close them all.
Push a plastic bi-fold door lock over the hinge of the first accordion door. Push a separate lock over the hinges of each door on the closet. When you push the lock into place, the handle should face outward toward you.
Push a provided shim up into the lock, between the plastic piece and the door, if the lock is loose. If the lock fits snugly, do not install the shim.