- An indirect firing fastening tool with an anti- firing trigger support. - The tool comprises, in one case (2), an axially movable eguipment (5) with a tip guide (6) projecting from the case to drive a fastening member into a support material, a reception housing (8) for a fastener charger and anti-firing safety means (11) to prevent the recoil of the tip guide, Advantageously, an anti-firing trigger (10) support (9) is mounted on said reception housing to convert the tool into a mono-firing tool, the trigger (10) being arranged to cooperate with the anti-firing safety means (11) so as to remove them and authorize firing.