A method of encoding video data comprising encoding a current picture of video data, generating a respective collocated reference picture index syntax element for one or more slices of the current picture, and performing a bitstream conformance check only for slices of the one or more slices that do not have an intra slice type and for which a temporal motion vector predictor is enabled, the bitstream conformance check constraining the values of the respective collocated reference picture index syntax elements such that each respective collocated reference picture index syntax element points to the same picture and does not reference the current picture itself.