An adjustment device for a motor vehicle seat that includes an electric motor, a gear connected to the electric motor, a mechanical adjustment unit connected to the gear and a control circuit, at least one sensor being associated with the control circuit for detecting a critical situation of the motor vehicle and the control circuit providing an operating voltage for the electric motor, characterized in that the control circuit provides as an alternative, in addition to the normal operating voltage, an overvoltage for supplying the electric motor, that the normal operating voltage applies in a normal driving condition of the motor vehicle in which the sensor does not deliver any signal, that the overvoltage applies at the electric motor in a driving condition after the sensor has delivered a signal indicating that the driving condition is no longer normal and that the overvoltage is at least 150% of the value of the normal operating voltage, more specifically at least 200% of the value of the normal operating voltage.