Generator rotor comprising a rotor rim and a plurality of permanent magnet modules arranged at one of an inner and outer circumference of said rotor rim, wherein the rotor rim comprises a plurality of rotor rings separated by gaps between them, and attached to each other via a plurality of axial strips fixed to the other of the inner and outer, the permanent magnet modules comprise a base and one or more rows of magnets mounted on a top surface of said base, and wherein the permanent magnet modules are fixed to the strips by a plurality of fasteners extending through the gaps between the rotor rings.