Embodiments of the invention provide a bone compression device for fixing first and second bone fragments together. The device includes an elongated fastener threadedly receivable within an anchor and a lock movably positioned within the anchor bore to lock the fastener and anchor against relative rotation. The lock may include an externally threaded locking screw threadedly receivable within the anchor coaxial with the fastener shank. The locking screw can be advanced within the anchor bore to lock the position of the fastener shank portion within the anchor bore. Embodiments of the device may be inserted within first and second bores formed in two bone fragments and tightened to compress the two bone fragments together.