A rotor of a fluid machine includes a wheel with a plurality of blades. Furthermore, the rotor includes an inter-blade area defined circumferentially between a first blade and a second blade of the plurality of blades with respect to the axis of rotation. Moreover, the rotor includes a balancing mark on the wheel and within the inter-blade area. The balancing mark is elongate and has a first end and a second end. The first end and the second end are stepped axially into the inter-blade area. The balancing mark extends arcuately between the first end and the second end. The balancing mark has a depth that varies as the balancing mark extends arcuately between the first end and the second end. The balancing mark has a width that varies as the balancing mark extends arcuately between the first end and the second end.