An LED driver configured to power a plurality of LEDs having a different colour or colour spectrum is described, the LED driver comprising: a power converter configured to supply power to the plurality of LEDs and a control unit, the control unit comprising: an input terminal configured to receive an input signal representing a desired colour set-point; a processing unit configured to: determine a MacAdam ellipse for the desired colour set-point; determine a required intensity or current for each of the plurality of LEDs so as to achieve the desired colour set-point; determine a colour shift direction for the colour set-point, based on the determined required intensities or currents; select a modified colour set-point based on the colour shift direction and the MacAdam ellipse; determine a required supply current for each of the plurality of LEDs so as to achieve the modified colour set-point; determine a control signal for the power converter so as to generate the required supply currents; and wherein the control unit further comprises an output terminal for outputting the control signal to the power converter.