The invention concerns a part of a turbomachine, including an element having a first aerodynamic surface including a counterbore at the bottom of which is provided a mounting hole of a fastening screw of the part, and a washer configured to be accommodate into the counterbore and intended to serve as a support for a head of the fastening screw, wherein the washer has an asymmetry of revolution about a screwing axis and is engaged by shape complementarity in the counterbore, and in that the washer includes a second aerodynamic surface extending in the continuity of the first surface.