diff --git a/src/phaseSystemModels/multiphaseInter/phasesSystem/multiphaseSystem/multiphaseSystem.C b/src/phaseSystemModels/multiphaseInter/phasesSystem/multiphaseSystem/multiphaseSystem.C
index 36066ac389..346e4aa664 100644
--- a/src/phaseSystemModels/multiphaseInter/phasesSystem/multiphaseSystem/multiphaseSystem.C
+++ b/src/phaseSystemModels/multiphaseInter/phasesSystem/multiphaseSystem/multiphaseSystem.C
@@ -358,6 +358,8 @@ void Foam::multiphaseSystem::solveAlphas()
                  Su + fvm::Sp(Sp, alpha1)
             );
 
+            alpha1Eqn.boundaryManipulate(alpha1.boundaryFieldRef());
+
             alpha1Eqn.solve();
 
             phiAlpha += alpha1Eqn.flux();