  We re-examine the model of Altarelli, Cabibbo, Corb\`{o}, Maiani and
Martinelli for inclusive semileptonic B decay, in the light of recent
calculations in heavy quark effective theory. The model can be shown to have
no~$1/m_b$ corrections, with a suitable definition of the b quark mass~$m_b$.
However, we find that the structure of the $1/m_b^2$~terms is incompatible with
the predictions of heavy quark effective theory. The numerical significance of
this discrepancy is discussed.
