Abstract: A turnbuckle comprising a frame delimiting an internal space and a cover pivotably attached to the frame. The frame including several cutout-outs giving access to the internal space of the frame, granting access to locking nut disposable therein. The cover includes one or more elongated members on an internal top cover surface that are configured to protrude through one or more slot openings on the frame when the cover is in a covering configuration. The cover is movable between a covering configuration and an uncovering configuration. In a covering configuration, the cover contacts the locking nut in at least three contact points, preventing rotational movement of the locking nut. In alternative embodiments, the cover may comprise a split cover, each independently attachable to the frame or a cover having a pair of aligned apertures configured to receive a pad lock to secure the cover in the covering configuration.