A circuit for adjusting a switching threshold of a touch probe, which has a touch element that can be deflected out of a position of repose and which upon a deflection of the touch element out of its position of repose causes a defined change in a measurable system parameter and outputs a switching signal when the value of the system parameter exceeds the switching threshold. The circuit includes a device for measuring the measurable system parameter, an electrical circuit for ascertaining a reference value from which the switching threshold is determinable and an incremental corrector that changes the value of the measurable reference value to the value of the measurable system parameter at the position of repose of the touch element, in which the switching threshold is determinable from the reference value.