  Using stability arguments, this Brief Report suggests that a term that
enhances the surface tension in the presence of large height fluctuations
should be included in the Kardar-Parisi-Zhang equation. A one-loop
renormalization group analysis then shows for interface dimensions larger than
$\simeq 3.3$ an unstable strong-coupling fixed point that enters the system
from infinity. The relevance of these results to the roughening transition is
discussed.
