In a testing overspeed protection system: a) on receiving an order to start a turbomachine, an electronic regulation system (ERS) of the turbomachine sends an order to a control circuit of a fuel cutoff member to close the fuel cutoff member or to keep it in the closed position; b) the closed state of the FCM is verified on the basis of information transmitted to the ERS and representative of the position of the FCM; c) if the result of the verification in b) is positive, the ERS sends an order to the FCM control circuit to authorize opening of the FCM and enable the starting procedure to continue; and d) if the result of the verification in b) is negative, the ERS issues fault information concerning the overspeed protection system.