The invention relates to a rotor for a non-positive-displacement machine, particularly a rotor for a compressor of a gas turbine, on which at least one shaft collar with an outer periphery and with two radially extending faces are placed. The rotor also comprises a multitude of retaining grooves for moving blades, said retaining grooves being provided on the outer periphery and extending transversal to the peripheral direction and each retaining groove has a groove bottom. In order to provide a rotor for a non-positive-displacement machine that makes it possible to reduce flow losses while having a simple geometrical design of the attachment of moving blades, the invention provides that an annual groove, which extends in an axial direction and which is coaxial to the rotation axis of the rotor, is provided at least on one face of the shaft collar. This annular groove is joined to the groove bottom of the retaining grooves whereby enabling material of the foot of the moving blade to be plastically forced into the annular groove.