Abstract: An apparatus for use with a control switch of a machine, such as an ignition switch of a motor vehicle, and with a locking device that is used to secure the machine when the machine is not in operation includes a covering that is detachably-attachable with respect to the control switch and the locking device. The covering is disposed in one of two positions. It is disposed in a first position over the control switch so as to prevent use of the control switch when the locking device is attached to the machine or it is disposed in a second position over a portion of the locking device so as to prevent use of the locking device when the locking device is not attached to the machine. When the covering is disposed over the control switch it serves as a reminder indicating that the locking device is attached to the machine. Alternative embodiments are described that provide various ways for making the covering and for attaching it to the control switch and to the locking device.