A workpiece is milled by a tool of a milling machine to form a desired freeform surface. For this purpose, the tool is moved relative to the workpiece along at least one tool path defined via support points. The support points of the or each tool path are defined either in workpiece coordinates or in machine coordinates. For each tool path, at least one spline is produced in connection with the support points. The or each spline is output to a control arrangement of the milling machine, which controls the motion of the tool along the or each tool path on the basis of the or each corresponding spline.