  Following the recent results from Daya Bay and RENO, which measure the lepton
mixing angle theta^l_13 ~ 0.15, we revisit a supersymmetric S4 x SU(5) model,
which predicts tri-bimaximal (TB) mixing in the neutrino sector with theta^l_13
being too small in its original version. We show that introducing one
additional S4 singlet flavon into the model gives rise to a sizable theta^l_13
via an operator which leads to the breaking of one of the two Z2 symmetries
preserved in the neutrino sector at leading order. The results of the original
model for fermion masses, quark mixing and the solar mixing angle are
maintained to good precision. The atmospheric and solar mixing angle deviations
from TB mixing are subject to simple sum rule bounds.
