  In this note we revisit Moussong's Characterization of Gromov-hyperbolic
Coxeter groups. A Coxeter group is Gromov-hyperbolic if and only if it does not
contain a subgroup isomorphic to $\mathbb{Z}^2$ which can be read off directly
from the defining graph. We show that there is a small gap in the original
argument and provide a workaround.
