A fastening assembly suitable for being fastened to a substrate with a front face and a first hole. The fastening assembly includes a fastening plate with a second plate with front and rear faces and pierced with a second hole aligned with the first hole. The fastening plate front face is fastened to the substrate rear face. The assembly includes a nut holder with a third plate with front and rear faces and pierced with a third hole aligned with the second hole and a nut fastened to the third plate on the side of the rear face and coaxial with the third hole. The front face of the nut holder is fastened to the rear face of the fastening plate. The fastening plate includes a first fastener that engages with a second fastener of the nut holder to removably fasten the nut holder to the fastening plate.