Gmx current dsp file

GROMACS version: 2018.3
GROMACS modification: No
Dear all,
In the output file dsp.xvg from gmx current command, I found the unit of scaled man-sqaured displacement of translational dipole moment (<|MJ(t)-MJ(0)|^2> /6VKBT) is Sm^-1ps^-1 which I think should be Sm^-1ps. The unit of 6VKBT is e^2nm^2ps^-1S^-1m and that of <|MJ(t)-MJ(0)|^2 is e^2nm^2. I can’t figure out what I am missing or doing wrong. Thanks for your patient reading. Any sort of help will be highly appreciated.