The invention relates to a method and an apparatus for repairing at least one defect of a photolithographic mask for the extreme ultraviolet (EUV) wavelength range, wherein the method includes the steps of: (a) determining the at least one defect; and (b) ascertaining a repair shape for the at least one defect; (c) wherein the repair shape is diffraction-based in order to take account of a phase disturbance by the at least one defect.