The present disclosure relates to a method for adjusting a bias voltage of a SPAD photodiode, comprising successive steps of: applying to the photodiode a first test bias voltage lower than a normal bias voltage applied to the photodiode in a normal operating mode, subjecting the photodiode to photons, reading a first avalanche triggering signal of the photodiode, applying to the photodiode a second test bias voltage, different from the first test bias voltage, subjecting the photodiode to photons, reading a second avalanche triggering signal of the photodiode, increasing the normal bias voltage if the first and second signals indicate that the photodiode did not avalanche trigger, and reducing the normal bias voltage if the first and second signals indicate that the photodiode did avalanche trigger.