diff --git a/applications/solvers/combustion/XiFoam/XiEngineFoam/XiEngineFoam.C b/applications/solvers/combustion/XiFoam/XiEngineFoam/XiEngineFoam.C
index 8aaa4333e2..1e5eb4b72e 100644
--- a/applications/solvers/combustion/XiFoam/XiEngineFoam/XiEngineFoam.C
+++ b/applications/solvers/combustion/XiFoam/XiEngineFoam/XiEngineFoam.C
@@ -78,7 +78,7 @@ int main(int argc, char *argv[])
     #include "readCombustionProperties.H"
     #include "createFields.H"
     #include "createFieldRefs.H"
-    #include "createRhoUf.H"
+    #include "createRhoUfIfPresent.H"
     #include "initContinuityErrs.H"
     #include "createEngineTimeControls.H"
     #include "compressibleCourantNo.H"
diff --git a/applications/solvers/combustion/XiFoam/XiEngineFoam/pEqn.H b/applications/solvers/combustion/XiFoam/XiEngineFoam/pEqn.H
index ef9a7a3d85..c1d9d2770e 100644
--- a/applications/solvers/combustion/XiFoam/XiEngineFoam/pEqn.H
+++ b/applications/solvers/combustion/XiFoam/XiEngineFoam/pEqn.H
@@ -15,7 +15,8 @@ if (pimple.transonic())
                 fvc::flux(HbyA)
               + MRF.zeroFilter
                 (
-                    rhorAUf*fvc::ddtCorr(rho, U, rhoUf)/fvc::interpolate(rho)
+                    rhorAUf*fvc::ddtCorr(rho, U, phi, rhoUf)
+                   /fvc::interpolate(rho)
                 )
             )
         )
@@ -48,10 +49,8 @@ else
     surfaceScalarField phiHbyA
     (
         "phiHbyA",
-        (
-            fvc::flux(rho*HbyA)
-          + MRF.zeroFilter(rhorAUf*fvc::ddtCorr(rho, U, rhoUf))
-        )
+        fvc::interpolate(rho)*fvc::flux(HbyA)
+      + MRF.zeroFilter(rhorAUf*fvc::ddtCorr(rho, U, phi, rhoUf))
     );
 
     fvc::makeRelative(phiHbyA, rho, U);
@@ -88,11 +87,8 @@ U.correctBoundaryConditions();
 fvConstraints.constrain(U);
 K = 0.5*magSqr(U);
 
-{
-    rhoUf = fvc::interpolate(rho*U);
-    surfaceVectorField n(mesh.Sf()/mesh.magSf());
-    rhoUf += n*(fvc::absolute(phi, rho, U)/mesh.magSf() - (n & rhoUf));
-}
+// Correct rhoUf if the mesh is moving
+fvc::correctRhoUf(rhoUf, rho, U, phi);
 
 if (thermo.dpdt())
 {
diff --git a/src/finiteVolume/finiteVolume/ddtSchemes/ddtScheme/ddtScheme.C b/src/finiteVolume/finiteVolume/ddtSchemes/ddtScheme/ddtScheme.C
index eb69175ac4..0cb2dc8f9f 100644
--- a/src/finiteVolume/finiteVolume/ddtSchemes/ddtScheme/ddtScheme.C
+++ b/src/finiteVolume/finiteVolume/ddtSchemes/ddtScheme/ddtScheme.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2019 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2021 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -184,7 +184,7 @@ tmp<surfaceScalarField> ddtScheme<Type>::fvcDdtPhiCoeff
     {
         if
         (
-            U.boundaryField()[patchi].fixesValue()
+            !U.boundaryField()[patchi].coupled()
          || isA<cyclicAMIFvPatch>(mesh().boundary()[patchi])
         )
         {