Let X be a scheme. Let a : X —> Spec(k₁) and b : X —> Spec(k₂) be morphisms from X to spectra of fields. Assume a,b are locally of finite type, and X is reduced, and connected. Then we have k′₁ = k′₂, where k′_i ⊂ Γ(X,O_X) is the integral closure of k_i in Γ(X,O_X). See Tag 04MK.