A fixing device (1) comprises: a first wing (10) inserted in a first profile (2), a second wing (11) inserted in a second profile (3); a threaded hole (5) obtained on each wing (10, 11); a screw (4) comprising a stem (40) screwed in the threaded hole (5), and a head (41) that tightens an upper edge (23, 33) of a profile (2, 3), a removable spacer (6) forming a space (G) between the head (41) of the screw (4) and the wind (10, 11); the space (G) receives the upper edge (23, 33) of the profile, without having to remove the screw (4) from the threaded hole (5) of the fixing device (1); the removable spacer (6) is removed by rubbing the head (41) of the screw (4) against the removable spacer (6) when screwing the screw (4) in the threaded hole (5).