diff --git a/applications/solvers/multiphase/multiphaseEulerFoam/pEqn.H b/applications/solvers/multiphase/multiphaseEulerFoam/pEqn.H
index 5e71a2eeeb..7b5b83784d 100644
--- a/applications/solvers/multiphase/multiphaseEulerFoam/pEqn.H
+++ b/applications/solvers/multiphase/multiphaseEulerFoam/pEqn.H
@@ -166,6 +166,9 @@
     {
         phaseModel& phase = iter();
 
+        phase.phi().boundaryField() ==
+            (mesh.Sf().boundaryField() & phase.U().boundaryField());
+
         mrfZones.relativeFlux(phase.phi().oldTime());
         mrfZones.relativeFlux(phase.phi());