  Recently a boundary energy-momentum tensor $T_{zz}$ has been constructed from
the soft graviton operator for any 4D quantum theory of gravity in
asymptotically flat space. Up to an "anomaly" which is one-loop exact, $T_{zz}$
generates a Virasoro action on the 2D celestial sphere at null infinity. Here
we show by explicit construction that the effects of the IR divergent part of
the anomaly can be eliminated by a one-loop renormalization that shifts
$T_{zz}$.
