Bi-directional optical flow (BDOF) is included in the VVC to enhance the granularity and accuracy of the motion vectors (MVs) used for motion compensation. It is reported that in the VVC working draft 5 the precisions of the intermediate parameters in the BDOF derivation are consistent when the internal bit-depth is 8-bit to 12-bit but inconsistent when the internal bit-depth is greater than 12-bit. In this contribution, it is proposed to unify the derivation precision of the BDOF for different internal bit-depths. Specifically, in the proposed method, the same BDOF derivation precision that is used for 8-bit to 12-bit is extended to be used for high internal bit-depth (i.e., > 12-bit). The proposed modification has no performance impact under the common test condition (CTC).