The invention describes a method of driving an arc-discharge lamp (1), which method comprises the steps of detecting a mechanically induced fluctuation in luminous flux of the lamp (1) occurring as a result of a physical displacement of the discharge arc (2), determining a characteristic (43, 51, 63) of the mechanically induced fluctuation in luminous flux of the lamp (1), and adjusting the lamp power on the basis of the determined characteristic (43, 51, 63) to suppress the mechanically induced fluctuation in luminous flux of the lamp (1). The invention further describes a driver (3) for an arc-discharge lamp (1), which driver comprises a detecting means (40, 50, 60) for detecting a mechanically induced fluctuation in luminous flux of the lamp (1) occurring as a result of a physical displacement of the discharge arc (2), a determination unit (42, 50, 62) for determining a characteristic (43, 51, 63) of the mechanically induced fluctuation in luminous flux of the lamp (1); and an adjustment unit (8) for adjusting a lamp power (Pc) on the basis of the determined characteristic (43, 51, 63) to suppress the mechanically induced fluctuation in luminous flux of the lamp (1). The invention also describes a lighting assembly (9) comprising a high-intensity gas-discharge lamp (1) and such a driver (3) for driving the lamp (1) according to the inventive method.