A seat belt retractor includes a housing and a spool supported by the housing. Webbing is wound around the spool. A webbing engagement member is supported by the housing and is movable to a locked position engaged with the webbing for preventing movement of the webbing relative to webbing engagement member. An activating device is slideably supported by the housing and is slideably engageable with the webbing engagement member for moving the webbing locking device to the locked position. In the locked position, the webbing locking device prevents the webbing from being fed from the spool, thus preventing any slack in the webbing on the spool from being fed out when the webbing locking device is in the locked position.