In one example, a device for coding video data includes a video coder configured to determine a first target reference index representing a reference picture to which a candidate motion vector predictor for a current motion vector refers, determine, for the candidate motion vector predictor and during temporal motion vector prediction (TMVP) of the current motion vector, a value for an additional target reference index that is equal to a predetermined value, and code the current motion vector based at least in part on the value of the additional reference index.