Abstract: There is described a fastening plug which comprises a substantially cylindrical portion with a center bore, ending in a collar which will bear on a surface of said wall, said cylindrical portion being extended by at least two outer wings which are joined at the opposite plug end, while two inner wings which are joined at the free end thereof and face said cylindrical portion, are so provided that a tightening member screwed into said bore and also going through those bores provided where said outer and inner wings meet, causes said outer wings to distort outwards as an overthickness to thus insure the locking of the plug on the wall.