1. A method of coding video data, the method comprising: determining a first target reference index representing a reference picture to which a candidate motion vector predictor for a current motion vector refers; determining, 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 coding the current motion vector based at least in part on the value of the additional reference index.