  We present the calculation of the $\mathcal{O}(\alpha_s^2 C_F T_F)$ massive
quark corrections to the soft function for the double hemisphere jet mass
distribution in $e^+ e^-$ collisions, a necessary ingredient for the
calculation of several event shape distributions at N${}^3$LL order. Using the
mass as an infrared regulator allows us to derive an expression for the
massless momentum space limit, which has not been given so far in the
literature. Furthermore, we compute the corresponding corrections in the soft
function for thrust, the most prominent projection of the double hemisphere
mass distribution. Finally we give expressions for the corresponding renormalon
subtractions in the gap scheme.
