  In this note, we show that if all Lyapunov exponents of a matrix cocycle
vanish, then it can be perturbed to become cohomologous to a cocycle taking
values in the orthogonal group. This extends a result of Avila, Bochi and
Damanik to general base dynamics and arbitrary dimension. We actually prove a
fibered version of this result, and apply it to study the existence of
dominated splittings into conformal subbundles of general matrix cocycles.
