diff --git a/src/finiteVolume/fvMesh/fvPatches/constraint/cyclicACMI/cyclicACMIFvPatch.C b/src/finiteVolume/fvMesh/fvPatches/constraint/cyclicACMI/cyclicACMIFvPatch.C
index 8aad764f9b..f02ce291c1 100644
--- a/src/finiteVolume/fvMesh/fvPatches/constraint/cyclicACMI/cyclicACMIFvPatch.C
+++ b/src/finiteVolume/fvMesh/fvPatches/constraint/cyclicACMI/cyclicACMIFvPatch.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2013-2018 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2013-2020 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -52,28 +52,28 @@ void Foam::cyclicACMIFvPatch::updateAreas() const
 
         // owner couple
         const_cast<vectorField&>(Sf()) = patch().faceAreas();
-        const_cast<scalarField&>(magSf()) = mag(patch().faceAreas());
+        const_cast<scalarField&>(magSf()) = patch().magFaceAreas();
 
         // owner non-overlapping
         const fvPatch& nonOverlapPatch = nonOverlapFvPatch();
         const_cast<vectorField&>(nonOverlapPatch.Sf()) =
             nonOverlapPatch.patch().faceAreas();
         const_cast<scalarField&>(nonOverlapPatch.magSf()) =
-            mag(nonOverlapPatch.patch().faceAreas());
+            nonOverlapPatch.patch().magFaceAreas();
 
         // neighbour couple
         const cyclicACMIFvPatch& nbrACMI = neighbFvPatch();
         const_cast<vectorField&>(nbrACMI.Sf()) =
             nbrACMI.patch().faceAreas();
         const_cast<scalarField&>(nbrACMI.magSf()) =
-            mag(nbrACMI.patch().faceAreas());
+            nbrACMI.patch().magFaceAreas();
 
         // neighbour non-overlapping
         const fvPatch& nbrNonOverlapPatch = nbrACMI.nonOverlapFvPatch();
         const_cast<vectorField&>(nbrNonOverlapPatch.Sf()) =
             nbrNonOverlapPatch.patch().faceAreas();
         const_cast<scalarField&>(nbrNonOverlapPatch.magSf()) =
-            mag(nbrNonOverlapPatch.patch().faceAreas());
+            nbrNonOverlapPatch.patch().magFaceAreas();
 
         // set the updated flag
         cyclicACMIPatch().setUpdated(false);
diff --git a/src/meshTools/AMIInterpolation/patches/cyclicACMI/cyclicACMIPolyPatch/cyclicACMIPolyPatch.C b/src/meshTools/AMIInterpolation/patches/cyclicACMI/cyclicACMIPolyPatch/cyclicACMIPolyPatch.C
index a2c9121312..3f93ebda52 100644
--- a/src/meshTools/AMIInterpolation/patches/cyclicACMI/cyclicACMIPolyPatch/cyclicACMIPolyPatch.C
+++ b/src/meshTools/AMIInterpolation/patches/cyclicACMI/cyclicACMIPolyPatch/cyclicACMIPolyPatch.C
@@ -73,6 +73,7 @@ void Foam::cyclicACMIPolyPatch::resetAMI() const
         // Trigger re-building of faceAreas
         (void)boundaryMesh().mesh().faceAreas();
 
+
         // Calculate the AMI using partial face-area-weighted. This leaves
         // the weights as fractions of local areas (sum(weights) = 1 means
         // face is fully covered)
@@ -92,12 +93,16 @@ void Foam::cyclicACMIPolyPatch::resetAMI() const
         if (srcMask_.size())
         {
             vectorField::subField Sf = faceAreas();
+            scalarField::subField magSf = magFaceAreas();
             vectorField::subField noSf = nonOverlapPatch.faceAreas();
+            scalarField::subField noMagSf = nonOverlapPatch.magFaceAreas();
 
             forAll(Sf, facei)
             {
                 Sf[facei] *= srcMask_[facei];
+                magSf[facei] = mag(Sf[facei]);
                 noSf[facei] *= 1.0 - srcMask_[facei];
+                noMagSf[facei] = mag(noSf[facei]);
             }
         }
         // Adapt slave side areas
@@ -108,12 +113,16 @@ void Foam::cyclicACMIPolyPatch::resetAMI() const
             const polyPatch& pp = cp.nonOverlapPatch();
 
             vectorField::subField Sf = cp.faceAreas();
+            scalarField::subField magSf = cp.magFaceAreas();
             vectorField::subField noSf = pp.faceAreas();
+            scalarField::subField noMagSf = pp.magFaceAreas();
 
             forAll(Sf, facei)
             {
                 Sf[facei] *= tgtMask_[facei];
+                magSf[facei] = mag(Sf[facei]);
                 noSf[facei] *= 1.0 - tgtMask_[facei];
+                noMagSf[facei] = mag(noSf[facei]);
             }
         }
 
@@ -403,8 +412,8 @@ Foam::label Foam::cyclicACMIPolyPatch::nonOverlapPatchID() const
 
         if (size() == noPp.size())
         {
-            const scalarField magSf(mag(faceAreas()));
-            const scalarField noMagSf(mag(noPp.faceAreas()));
+            const scalarField magSf(magFaceAreas());
+            const scalarField noMagSf(noPp.magFaceAreas());
 
             forAll(magSf, facei)
             {
diff --git a/src/meshTools/AMIInterpolation/patches/cyclicRepeatAMI/cyclicRepeatAMIPolyPatch/cyclicRepeatAMIPolyPatch.C b/src/meshTools/AMIInterpolation/patches/cyclicRepeatAMI/cyclicRepeatAMIPolyPatch/cyclicRepeatAMIPolyPatch.C
index efab8c0eab..ee9fd6b37b 100644
--- a/src/meshTools/AMIInterpolation/patches/cyclicRepeatAMI/cyclicRepeatAMIPolyPatch/cyclicRepeatAMIPolyPatch.C
+++ b/src/meshTools/AMIInterpolation/patches/cyclicRepeatAMI/cyclicRepeatAMIPolyPatch/cyclicRepeatAMIPolyPatch.C
@@ -127,8 +127,8 @@ void Foam::cyclicRepeatAMIPolyPatch::resetAMI() const
     // patch from its neighbour
     label n = 0;
     {
-        const scalarField thisMagAreas(mag(this->faceAreas()));
-        const scalarField nbrMagAreas(mag(nbrPatch().faceAreas()));
+        const scalarField thisMagAreas(this->magFaceAreas());
+        const scalarField nbrMagAreas(nbrPatch().magFaceAreas());
 
         vector thisCentre =
             gSum(this->faceCentres()*thisMagAreas)/gSum(thisMagAreas);