We propose a quark flavor model based on modular S'₄ with a general CP symmetry. CP violation in the quark sector is entirely realized by the modulus ⟨ τ⟩. We show that the canonical normalization induced by the Kähler metric plays a crucial role in reproducing the observed hierarchies, while maintaining coupling constants of order O(1). The minimal model achieves a great fit to the quark sector data, which we take as the PDG 2024 data extrapolated to the GUT scale.