A tensioner (10) for a vehicle safety device is provided with a tubular casing (12) in which a piston (18) is movably supported as well as with a closure member (26) closing the tubular casing (12) on the front face and forming a cable guide (38) for a tensioning cable (28) which may be connected to a belt buckle or an end fitting (34) and in which cable guide the tensioning cable (28) is deflected in arc shape. Further, the tensioner (10) comprises an inflator (24) accommodated in the closure member (26), wherein the tubular casing (12) includes a receiving area (14) for receiving the closure member (26) as well as a fastening portion (16) serving for fastening the tensioner (10) to a vehicle frame.