diff --git a/src/thermophysicalModels/multicomponentThermo/mixtures/basicSpecieMixture/basicSpecieMixtureI.H b/src/thermophysicalModels/multicomponentThermo/mixtures/basicSpecieMixture/basicSpecieMixtureI.H
index 16b6efa770..58bd99e3d4 100644
--- a/src/thermophysicalModels/multicomponentThermo/mixtures/basicSpecieMixture/basicSpecieMixtureI.H
+++ b/src/thermophysicalModels/multicomponentThermo/mixtures/basicSpecieMixture/basicSpecieMixtureI.H
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -124,7 +124,7 @@ inline Foam::label Foam::basicSpecieMixture::index
     const volScalarField& Yi
 ) const
 {
-    return species_[Yi.name()];
+    return species_[Yi.member()];
 }