Method for determining a constant parameter of an inhibition value, or constant inhibition parameter, for adjusting a mean operating frequency (Fhor) of an electronic watch including an electronic device comprising: - an internal time base comprising a time-measurement oscillator and a clock circuit, the time-measurement oscillator having a natural frequency (Fosc) and being arranged to provide a periodic time-measurement signal (Sosc) with said natural frequency (Fosc), the clock circuit being arranged to receive time-measurement signal (Sosc) and to provide a clock signal (Sh) with the mean operating frequency (Fhor), - a circuit for adjusting the mean operating frequency (Fhor), including a memory storing at least said constant inhibition parameter, the adjustment circuit being arranged to inhibit, by predefined inhibition period and as a function of at least the constant inhibition parameter, one or more periods in the generation of a periodic signal (Sint) internal to the clock circuit involved in the generation of the clock signal (Sh), such that the mean operating frequency is more precise, the periodic internal signal being derived from the time-measurement signal, the method for determining the constant inhibition parameter being characterized in that the method includes the following steps, consisting in: - ET1: from a first external pulse and a second external pulse received from a system external to the watch and separated by a measurement time (Tm) corresponding to a reference number (Nref) of reference periods (Pref) for a periodic calibration signal (Scal) derived from the time-measurement signal (Sosc) and having a calibration frequency (Fcal) derived from the natural frequency, determining a calibration parameter representative of a ratio between a calibration period (Pcal), equal to the inverse of the calibration frequency (Fcal), and the reference period (Pref), and - ET2: determining a constant inhibition parameter as a function of the calibration parameter. - an internal time base comprising a time-measurement oscillator and a clock circuit, the time-measurement oscillator having a natural frequency (Fosc) and being arranged to provide a periodic time-measurement signal (Sosc) with said natural frequency (Fosc), the clock circuit being arranged to receive time-measurement signal (Sosc) and to provide a clock signal (Sh) with the mean operating frequency (Fhor), - a circuit for adjusting the mean operating frequency (Fhor), including a memory storing at least said constant inhibition parameter, the adjustment circuit being arranged to inhibit, by predefined inhibition period and as a function of at least the constant inhibition parameter, one or more periods in the generation of a periodic signal (Sint) internal to the clock circuit involved in the generation of the clock signal (Sh), such that the mean operating frequency is more precise, the periodic internal signal being derived from the time-measurement signal, - ET1: from a first external pulse and a second external pulse received from a system external to the watch and separated by a measurement time (Tm) corresponding to a reference number (Nref) of reference periods (Pref) for a periodic calibration signal (Scal) derived from the time-measurement signal (Sosc) and having a calibration frequency (Fcal) derived from the natural frequency, determining a calibration parameter representative of a ratio between a calibration period (Pcal), equal to the inverse of the calibration frequency (Fcal), and the reference period (Pref), and - ET2: determining a constant inhibition parameter as a function of the calibration parameter.