diff --git a/src/finiteVolume/fvMesh/fvPatches/constraint/processor/processorFvPatch.C b/src/finiteVolume/fvMesh/fvPatches/constraint/processor/processorFvPatch.C
index 350a0b259..a0041ed22 100644
--- a/src/finiteVolume/fvMesh/fvPatches/constraint/processor/processorFvPatch.C
+++ b/src/finiteVolume/fvMesh/fvPatches/constraint/processor/processorFvPatch.C
@@ -26,6 +26,7 @@ License
 #include "processorFvPatch.H"
 #include "addToRunTimeSelectionTable.H"
 #include "transformField.H"
+#include "crMatrix.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -174,6 +175,35 @@ tmp<labelField> processorFvPatch::internalFieldTransfer
 }
 
 
+void processorFvPatch::initProlongationTransfer
+(
+    const Pstream::commsTypes commsType,
+    const crMatrix& P
+) const
+{
+    // Select the part of the prolongation matrix to send
+
+    // Send prolongation matrix
+    Pout<< "HJ, in send for processorFvPatch" << endl;
+}
+
+
+tmp<crMatrix> processorFvPatch::prolongationTransfer
+(
+    const Pstream::commsTypes commsType,
+    const crMatrix& P
+) const
+{
+    // Receive and return prolongation matrix
+    Pout<< "HJ, in receive for processorFvPatch" << endl;
+
+    // Dummy
+    tmp<crMatrix> tcr(new crMatrix(5, 5, labelList(5)));
+
+    return tcr;
+}
+
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace Foam
diff --git a/src/finiteVolume/fvMesh/fvPatches/constraint/processor/processorFvPatch.H b/src/finiteVolume/fvMesh/fvPatches/constraint/processor/processorFvPatch.H
index 76ecf7449..f3b724550 100644
--- a/src/finiteVolume/fvMesh/fvPatches/constraint/processor/processorFvPatch.H
+++ b/src/finiteVolume/fvMesh/fvPatches/constraint/processor/processorFvPatch.H
@@ -185,6 +185,22 @@ public:
                 const Pstream::commsTypes commsType,
                 const unallocLabelList& internalData
             ) const;
+
+            //- Initialise transfer of prolongation matrix to the interface
+            virtual void initProlongationTransfer
+            (
+                const Pstream::commsTypes commsType,
+                const crMatrix& iF
+            ) const;
+
+            //- Transfer and return prolongation matrix adjacent to
+            //  the interface
+            virtual tmp<crMatrix> prolongationTransfer
+            (
+                const Pstream::commsTypes commsType,
+                const crMatrix& iF
+            ) const;
+
 };
 
 
diff --git a/src/foam/matrices/lduMatrix/lduAddressing/lduInterfaces/lduInterface/lduInterface.C b/src/foam/matrices/lduMatrix/lduAddressing/lduInterfaces/lduInterface/lduInterface.C
index b31f82cc3..3a78b9eeb 100644
--- a/src/foam/matrices/lduMatrix/lduAddressing/lduInterfaces/lduInterface/lduInterface.C
+++ b/src/foam/matrices/lduMatrix/lduAddressing/lduInterfaces/lduInterface/lduInterface.C
@@ -46,7 +46,7 @@ Foam::lduInterface::~lduInterface()
 Foam::tmp<Foam::crMatrix> Foam::lduInterface::prolongationTransfer
 (
     const Pstream::commsTypes commsType,
-    const crMatrix& iF
+    const crMatrix& P
 ) const
 {
     notImplemented
@@ -54,9 +54,13 @@ Foam::tmp<Foam::crMatrix> Foam::lduInterface::prolongationTransfer
         "tmp<crMatrix> lduInterface::prolongationTransfer\n"
         "(\n"
         "    const Pstream::commsTypes commsType,\n"
-        "    const crMatrix& iF\n"
-        ") const"
+        "    const crMatrix& P\n"
+        ") const for type " +
+        this->type()
     );
+
+    // Dummy return to make the compiler happy
+    return P;
 }
 
 
diff --git a/src/foam/matrices/lduMatrix/solvers/AMG/interfaces/SAMGInterfaces/SAMGInterface/SAMGInterface.H b/src/foam/matrices/lduMatrix/solvers/AMG/interfaces/SAMGInterfaces/SAMGInterface/SAMGInterface.H
index c5b45ba0b..0389759d4 100644
--- a/src/foam/matrices/lduMatrix/solvers/AMG/interfaces/SAMGInterfaces/SAMGInterface/SAMGInterface.H
+++ b/src/foam/matrices/lduMatrix/solvers/AMG/interfaces/SAMGInterfaces/SAMGInterface/SAMGInterface.H
@@ -66,7 +66,7 @@ class SAMGInterface
         const crMatrix& prolongation_;
 
         //- Reference to prolongation matrix
-        const crMatrix& nbrInterfaceProlongation_;
+        const crMatrix nbrInterfaceProlongation_;
 
 
 protected:
diff --git a/src/foam/matrices/lduMatrix/solvers/AMG/interfaces/SAMGInterfaces/processorSAMGInterface/processorSAMGInterface.C b/src/foam/matrices/lduMatrix/solvers/AMG/interfaces/SAMGInterfaces/processorSAMGInterface/processorSAMGInterface.C
index 92178d37e..bbf004450 100644
--- a/src/foam/matrices/lduMatrix/solvers/AMG/interfaces/SAMGInterfaces/processorSAMGInterface/processorSAMGInterface.C
+++ b/src/foam/matrices/lduMatrix/solvers/AMG/interfaces/SAMGInterfaces/processorSAMGInterface/processorSAMGInterface.C
@@ -305,7 +305,7 @@ Foam::tmp<Foam::labelField> Foam::processorSAMGInterface::internalFieldTransfer
 void Foam::processorSAMGInterface::initProlongationTransfer
 (
     const Pstream::commsTypes commsType,
-    const crMatrix& iF
+    const crMatrix& P
 ) const
 {
     // Select the part of the prolongation matrix to send
@@ -317,7 +317,7 @@ void Foam::processorSAMGInterface::initProlongationTransfer
 Foam::tmp<Foam::crMatrix> Foam::processorSAMGInterface::prolongationTransfer
 (
     const Pstream::commsTypes commsType,
-    const crMatrix& iF
+    const crMatrix& P
 ) const
 {
     // Receive and return prolongation matrix