A device for fastening a moving blade (3) to a rotor (2) of a thermal turbomachine is described. The moving blade (3) has a blade root (36), a blade leaf (32) and a platform (31) arranged between the blade root (36) and the blade leaf (32) and having at least two side flanks (33, 34). The idea, on which the invention is based, of avoiding axial forces occurring on the rotor (2) on account of bearing faces set obliquely to the rotor axis (4) between two adjacent moving blades (3) is that adjacent moving blades (3) meet solely at axially oriented bearing faces (52).