A method and cruise control system for controlling a vehicle cruise control includes driving the vehicle with the cruise control active and set to maintain a vehicle set target speed, and registering a current vehicle condition, which includes at least a current vehicle position, a currently engaged gear ratio, available gear ratios, current vehicle speed, available maximum propulsion torque and road topography of coming travelling road comprising a next coming uphill slope. Based on the current vehicle condition a downshift is predicted at a coming vehicle position in the coming uphill slope due to vehicle speed decrease and at least one activity is selected which results in that the downshift can be postponed or avoided. The cruise control is controlled according to the selected activity in order to postpone or avoid, for example a downshift from a direct gear and thereby saves fuel.