Let T be a linear operator on a Banach space X with $supₙ ||Tⁿ/n^{w}|| < ∞ $ for some 0 ≤ w < 1. We show that the following conditions are equivalent: (i) $n^{-1} ∑_{k=0}^{n-1} T^{k}$ converges uniformly; (ii) $cl(I -T)X = {z ∈ X : lim_{n} ∑_{k=1}^{n} T^{k}z/k exists}$.