The invention relates to a swivelable roll bar, in particular for construction vehicles, with two vertical carriers, each of which has a pair of spars, whereby in each, one spar is connected swivelably through a link joint with the another spar, and the link joint comprises a lock and a stop. The stop consists of a joint stiffener, which is built as an extension of one spar and partially grips about the end of the other. In addition to that, the lock has a continuously adjustable final control element, with which the joint stiffener can be braced against the other spar. With the grip about the other spar, the flexural strength of the link joint of the swivelable roll bar is increased. Further, the bracing of the joint stiffener against the other spar eliminates the play in the link joint. The joint stiffener is preferably built as a U-shaped tubular segment that is attached to the latter as an extension of the spar.