  We calculate the three-loop master integrals of Ref. [1] [arXiv:1709.02160]
in analytic form. This allows us to present the fermionic contributions to the
$\Delta B=2$ Wilson coefficients of the $B$-$\bar B$ decay matrix in
next-to-next-to-leading order of QCD with full analytic dependence on the mass
of the charm quark in the fermionic loops.
