A circuit for monitoring a switching state of a mechanical switch is provided that includes a first mechanical switch configured to couple a high-voltage power storage device to a load, a measuring device that measures a voltage characteristic at the first mechanical switch, the measuring device is being connected to the first mechanical switch via a first measuring resistor such that a voltage drop at the first mechanical switch is measurable over a period of time, an insulation-monitoring unit having a first switchable resistor that can be switched in during measuring such that a voltage divider formed by two or more insulation resistors (R_iso+, R_iso−) of the high-voltage power storage device is modified, and an evaluation device that compares the measured voltage characteristic at the first mechanical switch with a predefined threshold value so that the switching state of the first mechanical switch can be determined.