diff --git a/src/fvAgglomerationMethods/MGridGenGamgAgglomeration/MGridGenGAMGAgglomerate.C b/src/fvAgglomerationMethods/MGridGenGamgAgglomeration/MGridGenGAMGAgglomerate.C
index 5545ce4c0..a5fcc6d68 100644
--- a/src/fvAgglomerationMethods/MGridGenGamgAgglomeration/MGridGenGAMGAgglomerate.C
+++ b/src/fvAgglomerationMethods/MGridGenGamgAgglomeration/MGridGenGAMGAgglomerate.C
@@ -31,10 +31,16 @@ Description
 #include "fvMesh.H"
 #include "syncTools.H"
 
-//extern "C"
-//{
-//#   include "mgridgen.h"
-//}
+extern "C"
+{
+#   include "mgridgen.h"
+#   ifdef darwin
+#       undef FALSE
+#       undef TRUE
+#   endif
+
+#undef sign
+}
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
@@ -42,8 +48,8 @@ void Foam::MGridGenGAMGAgglomeration::
 makeCompactCellFaceAddressingAndFaceWeights
 (
     const lduAddressing& fineAddressing,
-    List<idxtype>& cellCells,
-    List<idxtype>& cellCellOffsets,
+    labelList& cellCells,
+    labelList& cellCellOffsets,
     const vectorField& Si,
     List<scalar>& faceWeights
 )
@@ -113,8 +119,8 @@ Foam::tmp<Foam::labelField> Foam::MGridGenGAMGAgglomeration::agglomerate
     const label nFineCells = fineAddressing.size();
 
     // Compact addressing for cellCells
-    List<idxtype> cellCells;
-    List<idxtype> cellCellOffsets;
+    labelList cellCells;
+    labelList cellCellOffsets;
 
     // Face weights = face areas of the internal faces
     List<scalar> faceWeights;
@@ -130,7 +136,7 @@ Foam::tmp<Foam::labelField> Foam::MGridGenGAMGAgglomeration::agglomerate
     );
 
     // MGridGen agglomeration options.
-    List<int> options(4, 0);
+    labelList options(4, 0);
     options[0] = 4;                   // globular agglom
     options[1] = 6;                   // objective F3 and F2
     options[2] = 128;                 // debugging output level
diff --git a/src/fvAgglomerationMethods/MGridGenGamgAgglomeration/MGridGenGAMGAgglomeration.H b/src/fvAgglomerationMethods/MGridGenGamgAgglomeration/MGridGenGAMGAgglomeration.H
index e26503074..f92fede7a 100644
--- a/src/fvAgglomerationMethods/MGridGenGamgAgglomeration/MGridGenGAMGAgglomeration.H
+++ b/src/fvAgglomerationMethods/MGridGenGamgAgglomeration/MGridGenGAMGAgglomeration.H
@@ -40,16 +40,6 @@ SourceFiles
 #include "fvMesh.H"
 #include "GAMGAgglomeration.H"
 
-extern "C"
-{
-#   include "mgridgen.h"
-#   ifdef darwin
-#       undef FALSE
-#       undef TRUE
-#   endif
-}
-
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
@@ -76,8 +66,8 @@ class MGridGenGAMGAgglomeration
         void makeCompactCellFaceAddressingAndFaceWeights
         (
             const lduAddressing& fineAddressing,
-            List<idxtype>& cellCells,
-            List<idxtype>& cellCellOffsets,
+            labelList& cellCells,
+            labelList& cellCellOffsets,
             const vectorField& Si,
             List<scalar>& faceWeights
         );