Generator rotor comprising a rotor rim and a plurality of permanent magnet modules and a plurality of anchors arranged at an outer or inner circumference of the rotor rim such that the anchors substantially fix the permanent magnet modules to the rotor, wherein the permanent magnet modules comprise a base having a bottom surface, two axially extending side surfaces and a top surface, and one or more rows of magnets mounted on said top surface, wherein the two side surfaces of the permanent magnet modules each comprise an axially extending groove, and wherein the anchors have a shape that substantially fits exactly in axially extending grooves of neighbouring permanent magnet modules.