  Let $\mathfrak{q}$ be an ideal of a Noetherian local ring $(A,\mathfrak{m})$
and $M$ a non-zero finitely generated $A$-module. We present a criterion of
Cohen-Macaulayness of the form module $G_M(\mathfrak{q})$ in terms of
(non-)vanishing of a variation of local cohomology introduced in \cite{KSch}.
