For the linear parameters, we impose the uniform-electron gas limit c 0 x + c sr x = 1, the longrange exchange limit (c lr x = 1), and the correct leading-order dispersion behavior (s 6 = 1.0). The remaining linear parameters may then be fitted using least-squares regression, with the power series expansions of the B97 functionals all calculated up to fourth order. Fitting is performed using energy components calculated on a fixed set of orbitals, therefore we must choose a functional with which to calculate the initial orbitals. Unlike the optimizations of ωB97X-V and ωB97M-V we chose an established functional to calculate the initial orbitals, namely ωB97X. The fitting procedure starts with the basic functional containing all zeroth order B97 components, the long-and short-range HF exchange, and the D3(BJ) components. This functional is optimized using a (weighted) linear regression on the training set. All possible combinations of additional parameters are added to this initial functional and re-optimized.