A hand tool for gripping a workpiece can include a first lever having a first handle and a first jaw and a second lever having a second handle and a second jaw. A locking assembly can include a pivoting lever, a locking pin and a blocking member. The pivoting lever can be pivotally coupled to the second lever. The blocking member can be coupled to the first lever. The pivoting lever can be movable between an unlocked position, wherein the first and second jaw move relative to each other and a locked position, wherein the first and second jaws are fixed relative to each other. In the locked position, the locking pin can be wedged against a contact surface of the blocking member precluding relative motion of the blocking member and the pivoting lever.