There is provided an improved clamping lock for tie rod ends in form structures for settable casting compositions, e.g., concrete casting forms, which lock is characterized by means for attaching it to the form structure, and a pair of jaws shaped for mating coaction with the outer end of a tie rod end whereby relative axial movement of the lock with respect to the tie rod end is prevented and the form structure is correspondingly held against movement toward or away from an opposite form structure.