diff --git a/src/OpenFOAM/matrices/LUscalarMatrix/LUscalarMatrix.C b/src/OpenFOAM/matrices/LUscalarMatrix/LUscalarMatrix.C
index 03dc2d5536..121f016c2f 100644
--- a/src/OpenFOAM/matrices/LUscalarMatrix/LUscalarMatrix.C
+++ b/src/OpenFOAM/matrices/LUscalarMatrix/LUscalarMatrix.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2004-2010 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2004-2011 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -260,6 +260,11 @@ void Foam::LUscalarMatrix::convert
             }
             else if (interface.myProcNo_ < interface.neighbProcNo_)
             {
+                // Interface to neighbour proc. Find on neighbour proc the
+                // corresponding interface. The problem is that there can
+                // be multiple interfaces between two processors (from
+                // processorCyclics) so also compare the communication tag
+
                 const PtrList<procLduInterface>& neiInterfaces =
                     lduMatrices[interface.neighbProcNo_].interfaces_;
 
@@ -269,8 +274,11 @@ void Foam::LUscalarMatrix::convert
                 {
                     if
                     (
-                        neiInterfaces[ninti].neighbProcNo_
-                     == interface.myProcNo_
+                        (
+                            neiInterfaces[ninti].neighbProcNo_
+                         == interface.myProcNo_
+                        )
+                     && (neiInterfaces[ninti].tag_ ==  interface.tag_)
                     )
                     {
                         neiInterfacei = ninti;
diff --git a/src/OpenFOAM/matrices/LUscalarMatrix/procLduInterface.C b/src/OpenFOAM/matrices/LUscalarMatrix/procLduInterface.C
index 0a4b713202..979ef37027 100644
--- a/src/OpenFOAM/matrices/LUscalarMatrix/procLduInterface.C
+++ b/src/OpenFOAM/matrices/LUscalarMatrix/procLduInterface.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2004-2010 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2004-2011 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -39,7 +39,8 @@ Foam::procLduInterface::procLduInterface
     faceCells_(interface.interface().faceCells()),
     coeffs_(coeffs),
     myProcNo_(-1),
-    neighbProcNo_(-1)
+    neighbProcNo_(-1),
+    tag_(-1)
 {
     if (isA<processorLduInterface>(interface.interface()))
     {
@@ -48,6 +49,7 @@ Foam::procLduInterface::procLduInterface
 
         myProcNo_ = pldui.myProcNo();
         neighbProcNo_ = pldui.neighbProcNo();
+        tag_ = pldui.tag();
     }
     else if (isA<cyclicLduInterface>(interface.interface()))
     {
@@ -70,7 +72,8 @@ Foam::procLduInterface::procLduInterface(Istream& is)
     faceCells_(is),
     coeffs_(is),
     myProcNo_(readLabel(is)),
-    neighbProcNo_(readLabel(is))
+    neighbProcNo_(readLabel(is)),
+    tag_(readLabel(is))
 {}
 
 
@@ -81,7 +84,8 @@ Foam::Ostream& Foam::operator<<(Ostream& os, const procLduInterface& cldui)
     os  << cldui.faceCells_
         << cldui.coeffs_
         << cldui.myProcNo_
-        << cldui.neighbProcNo_;
+        << cldui.neighbProcNo_
+        << cldui.tag_;
 
     return os;
 }
diff --git a/src/OpenFOAM/matrices/LUscalarMatrix/procLduInterface.H b/src/OpenFOAM/matrices/LUscalarMatrix/procLduInterface.H
index 0e03bfdb37..defaa331ff 100644
--- a/src/OpenFOAM/matrices/LUscalarMatrix/procLduInterface.H
+++ b/src/OpenFOAM/matrices/LUscalarMatrix/procLduInterface.H
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2004-2010 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2004-2011 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -57,6 +57,7 @@ class procLduInterface
         scalarField coeffs_;
         label myProcNo_;
         label neighbProcNo_;
+        label tag_;
 
 
     // Private Member Functions