For a block of video data, a video encoder can signal to a video decoder, using a context-based adaptive binary arithmetic coding (CABAC) process, a selected intra-prediction mode using a codeword that is mapped to a modified intra-prediction mode index. The video decoder can perform a context-based adaptive binary arithmetic coding (CABAC) process to determine the codeword signaled by the video encoder, determine the modified intra-prediction mode index corresponding to the codeword, determine most probable modes based on a context, map the modified intra-prediction mode index to an intra-prediction mode index by comparing the modified intra-prediction mode index to the mode indexes of the most probable modes, and determine the selected intra-prediction mode used to encode the block of video data based on the intra-prediction mode index.