diff --git a/applications/utilities/mesh/conversion/fluent3DMeshToFoam/fluent3DMeshToFoam.L b/applications/utilities/mesh/conversion/fluent3DMeshToFoam/fluent3DMeshToFoam.L
index ab1143b871..ae658b0af1 100644
--- a/applications/utilities/mesh/conversion/fluent3DMeshToFoam/fluent3DMeshToFoam.L
+++ b/applications/utilities/mesh/conversion/fluent3DMeshToFoam/fluent3DMeshToFoam.L
@@ -1257,23 +1257,6 @@ int main(int argc, char *argv[])
         );
     }
 
-    // Modify cells to be in zones as required
-    forAll(cellZoneIDs, cellZonei)
-    {
-        label cgi = cellZoneIDs[cellZonei];
-
-        for
-        (
-            label celli = cellGroupStartIndex[cgi];
-            celli <= cellGroupEndIndex[cgi];
-            celli++
-        )
-        {
-            meshMod.modifyCell(celli, cellZonei);
-        }
-    }
-
-
     bool doneWarning = false;
 
     // Add faceZone faces
@@ -1462,6 +1445,21 @@ int main(int argc, char *argv[])
         polyMeshUnMergeCyclics(mesh);
     }
 
+    // Add the cell zones as required
+    forAll(cellZoneIDs, cellZonei)
+    {
+        const label cgi = cellZoneIDs[cellZonei];
+
+        mesh.cellZones()[cellZonei].insert
+        (
+            identityMap
+            (
+                cellGroupStartIndex[cgi],
+                cellGroupEndIndex[cgi] + 1 - cellGroupStartIndex[cgi]
+            )
+        );
+    }
+
     mesh.setInstance(runTime.constant());
 
     // Set the precision of the points data to 10
diff --git a/applications/utilities/mesh/manipulation/createPatch/createPatch.C b/applications/utilities/mesh/manipulation/createPatch/createPatch.C
index 502a383429..f7be711104 100644
--- a/applications/utilities/mesh/manipulation/createPatch/createPatch.C
+++ b/applications/utilities/mesh/manipulation/createPatch/createPatch.C
@@ -500,7 +500,7 @@ int main(int argc, char *argv[])
     forAll(patchSources, addedI)
     {
         const dictionary& dict = patchSources[addedI];
-        addedPatchNames.insert(dict.lookup("name"));
+        addedPatchNames.insert(dict.lookup<word>("name"));
     }
 
 
diff --git a/applications/utilities/postProcessing/foamPostProcess/foamPostProcess.C b/applications/utilities/postProcessing/foamPostProcess/foamPostProcess.C
index 4649618d8c..5d22d3cf2d 100644
--- a/applications/utilities/postProcessing/foamPostProcess/foamPostProcess.C
+++ b/applications/utilities/postProcessing/foamPostProcess/foamPostProcess.C
@@ -305,7 +305,7 @@ int main(int argc, char *argv[])
         }
         if (args.optionFound("field"))
         {
-            requiredFields.insert(args.optionLookup("field")());
+            requiredFields.insert(word(args.optionLookup("field")()));
         }
     }
 
diff --git a/src/OpenFOAM/containers/HashTables/HashSet/HashSet.C b/src/OpenFOAM/containers/HashTables/HashSet/HashSet.C
index 73886cb9b4..251a2909a2 100644
--- a/src/OpenFOAM/containers/HashTables/HashSet/HashSet.C
+++ b/src/OpenFOAM/containers/HashTables/HashSet/HashSet.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2020 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2024 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -67,12 +67,12 @@ Foam::HashSet<Key, Hash>::HashSet
     for
     (
         typename HashTable<AnyType, Key, AnyHash>::const_iterator
-        cit = h.cbegin();
-        cit != h.cend();
-        ++cit
+        iter = h.cbegin();
+        iter != h.cend();
+        ++iter
     )
     {
-        this->insert(cit.key());
+        this->insert(iter.key());
     }
 }
 
@@ -110,6 +110,22 @@ Foam::label Foam::HashSet<Key, Hash>::insert(const UList<Key>& lst)
 }
 
 
+template<class Key, class Hash>
+Foam::label Foam::HashSet<Key, Hash>::insert(const HashSet<Key>& set)
+{
+    label count = 0;
+    for (const_iterator iter = set.cbegin(); iter != set.cend(); ++iter)
+    {
+        if (this->insert(iter.key()))
+        {
+            ++count;
+        }
+    }
+
+    return count;
+}
+
+
 // * * * * * * * * * * * * * * * Member Operators  * * * * * * * * * * * * * //
 
 template<class Key, class Hash>
diff --git a/src/OpenFOAM/containers/HashTables/HashSet/HashSet.H b/src/OpenFOAM/containers/HashTables/HashSet/HashSet.H
index a51f40e7c2..43ba8fb7ab 100644
--- a/src/OpenFOAM/containers/HashTables/HashSet/HashSet.H
+++ b/src/OpenFOAM/containers/HashTables/HashSet/HashSet.H
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2021 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2024 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -106,8 +106,6 @@ public:
 
     // Member Functions
 
-        // Edit
-
         //- Insert a new entry
         bool insert(const Key& key)
         {
@@ -118,6 +116,10 @@ public:
         //  Return the number of new elements inserted
         label insert(const UList<Key>&);
 
+        //- Insert keys from a HashSet of Key
+        //  Return the number of new elements inserted
+        label insert(const HashSet<Key>&);
+
         //- Same as insert (cannot overwrite nil content)
         bool set(const Key& key)
         {
diff --git a/src/OpenFOAM/containers/HashTables/HashTable/HashTable.C b/src/OpenFOAM/containers/HashTables/HashTable/HashTable.C
index 24d91f576d..0792ac92b0 100644
--- a/src/OpenFOAM/containers/HashTables/HashTable/HashTable.C
+++ b/src/OpenFOAM/containers/HashTables/HashTable/HashTable.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2021 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2024 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -305,6 +305,26 @@ bool Foam::HashTable<T, Key, Hash>::set
 }
 
 
+template<class T, class Key, class Hash>
+void Foam::HashTable<T, Key, Hash>::insert(const HashTable<T, Key, Hash>& ht)
+{
+    for (const_iterator iter = ht.cbegin(); iter != ht.cend(); ++iter)
+    {
+        insert(iter.key(), *iter);
+    }
+}
+
+
+template<class T, class Key, class Hash>
+void Foam::HashTable<T, Key, Hash>::set(const HashTable<T, Key, Hash>& ht)
+{
+    for (const_iterator iter = ht.cbegin(); iter != ht.cend(); ++iter)
+    {
+        set(iter.key(), *iter);
+    }
+}
+
+
 template<class T, class Key, class Hash>
 bool Foam::HashTable<T, Key, Hash>::iteratorBase::erase()
 {
diff --git a/src/OpenFOAM/containers/HashTables/HashTable/HashTable.H b/src/OpenFOAM/containers/HashTables/HashTable/HashTable.H
index 589b285cd9..0b1eb2577a 100644
--- a/src/OpenFOAM/containers/HashTables/HashTable/HashTable.H
+++ b/src/OpenFOAM/containers/HashTables/HashTable/HashTable.H
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2024 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -259,9 +259,16 @@ public:
             //- Insert a new hashedEntry
             inline bool insert(const Key&, const T& newElmt);
 
-            //- Assign a new hashedEntry, overwriting existing entries
+            //- Insert all the entries from the given HashTable
+            void insert(const HashTable<T, Key, Hash>&);
+
+            //- Set a new hashedEntry, overwriting existing entries
             inline bool set(const Key&, const T& newElmt);
 
+            //- Insert all the entries from the given HashTable,
+            //  overwriting existing entries
+            void set(const HashTable<T, Key, Hash>&);
+
             //- Erase a hashedEntry specified by given iterator
             //  This invalidates the iterator until the next operator++
             bool erase(const iterator&);
diff --git a/src/OpenFOAM/containers/Lists/ListOps/ListOps.C b/src/OpenFOAM/containers/Lists/ListOps/ListOps.C
index 2e40db58d1..dc5e23350b 100644
--- a/src/OpenFOAM/containers/Lists/ListOps/ListOps.C
+++ b/src/OpenFOAM/containers/Lists/ListOps/ListOps.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2023 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2024 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -113,4 +113,16 @@ Foam::labelList Foam::identityMap(const label len)
 }
 
 
+Foam::labelList Foam::identityMap(const label start, const label len)
+{
+    labelList map(len);
+
+    forAll(map, i)
+    {
+        map[i] = start + i;
+    }
+    return map;
+}
+
+
 // ************************************************************************* //
diff --git a/src/OpenFOAM/containers/Lists/ListOps/ListOps.H b/src/OpenFOAM/containers/Lists/ListOps/ListOps.H
index 60548149f3..8c70dc7307 100644
--- a/src/OpenFOAM/containers/Lists/ListOps/ListOps.H
+++ b/src/OpenFOAM/containers/Lists/ListOps/ListOps.H
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2023 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2024 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -169,6 +169,9 @@ List<OutList> invertManyToMany(const label len, const UList<InList>& in)
 //- Create identity map (map[i] == i) of given length
 labelList identityMap(const label len);
 
+//- Create identity map (map[i] == start + i) of given length
+labelList identityMap(const label start, const label len);
+
 //- Count the number of occurrences of a value in a list
 template<class ListType>
 label count(const ListType& l, typename ListType::const_reference x);
diff --git a/src/OpenFOAM/meshes/polyMesh/zones/cellZone/cellZone.H b/src/OpenFOAM/meshes/polyMesh/zones/cellZone/cellZone.H
index 49d89e16c8..a728f7d548 100644
--- a/src/OpenFOAM/meshes/polyMesh/zones/cellZone/cellZone.H
+++ b/src/OpenFOAM/meshes/polyMesh/zones/cellZone/cellZone.H
@@ -49,12 +49,6 @@ SourceFiles
 namespace Foam
 {
 
-// Forward declaration of friend functions and operators
-
-class cellZone;
-Ostream& operator<<(Ostream&, const cellZone&);
-
-
 /*---------------------------------------------------------------------------*\
                           Class cellZone Declaration
 \*---------------------------------------------------------------------------*/
@@ -77,7 +71,7 @@ public:
     // Static Data Members
 
         //- The name associated with the zone-labels dictionary entry
-        static const char * const labelsName;
+        static const char* const labelsName;
 
 
     //- Runtime type information
@@ -219,12 +213,6 @@ public:
 
         //- Move assignment to zone, clearing demand-driven data
         void operator=(cellZone&&);
-
-
-    // I-O
-
-        //- Ostream Operator
-        friend Ostream& operator<<(Ostream&, const cellZone&);
 };
 
 
diff --git a/src/OpenFOAM/meshes/polyMesh/zones/faceZone/faceZone.H b/src/OpenFOAM/meshes/polyMesh/zones/faceZone/faceZone.H
index 61af4a7f0c..9dab0e5b07 100644
--- a/src/OpenFOAM/meshes/polyMesh/zones/faceZone/faceZone.H
+++ b/src/OpenFOAM/meshes/polyMesh/zones/faceZone/faceZone.H
@@ -117,7 +117,7 @@ public:
     // Static Data Members
 
         //- The name associated with the zone-labels dictionary entry
-        static const char * const labelsName;
+        static const char* const labelsName;
 
 
     //- Runtime type information
diff --git a/src/OpenFOAM/meshes/polyMesh/zones/pointZone/pointZone.C b/src/OpenFOAM/meshes/polyMesh/zones/pointZone/pointZone.C
index b832239303..e02e8c42f2 100644
--- a/src/OpenFOAM/meshes/polyMesh/zones/pointZone/pointZone.C
+++ b/src/OpenFOAM/meshes/polyMesh/zones/pointZone/pointZone.C
@@ -207,14 +207,4 @@ void Foam::pointZone::operator=(pointZone&& zn)
 }
 
 
-// * * * * * * * * * * * * * * * Ostream Operator  * * * * * * * * * * * * * //
-
-Foam::Ostream& Foam::operator<<(Ostream& os, const pointZone& zn)
-{
-    zn.write(os);
-    os.check("Ostream& operator<<(Ostream&, const pointZone&");
-    return os;
-}
-
-
 // ************************************************************************* //
diff --git a/src/OpenFOAM/meshes/polyMesh/zones/pointZone/pointZone.H b/src/OpenFOAM/meshes/polyMesh/zones/pointZone/pointZone.H
index fad4e97e5f..29bc4d5ffe 100644
--- a/src/OpenFOAM/meshes/polyMesh/zones/pointZone/pointZone.H
+++ b/src/OpenFOAM/meshes/polyMesh/zones/pointZone/pointZone.H
@@ -50,12 +50,6 @@ SourceFiles
 namespace Foam
 {
 
-// Forward declaration of friend functions and operators
-
-class pointZone;
-Ostream& operator<<(Ostream&, const pointZone&);
-
-
 /*---------------------------------------------------------------------------*\
                           Class pointZone Declaration
 \*---------------------------------------------------------------------------*/
@@ -78,7 +72,7 @@ public:
     // Static Data Members
 
         //- The name associated with the zone-labels dictionary entry
-        static const char * const labelsName;
+        static const char* const labelsName;
 
 
     //- Runtime type information
@@ -217,12 +211,6 @@ public:
 
         //- Move assignment to zone, clearing demand-driven data
         void operator=(pointZone&&);
-
-
-    // I-O
-
-        //- Ostream Operator
-        friend Ostream& operator<<(Ostream&, const pointZone&);
 };
 
 
diff --git a/src/OpenFOAM/meshes/polyMesh/zones/zone/zone.C b/src/OpenFOAM/meshes/polyMesh/zones/zone/zone.C
index 711d4583d5..325574d1a4 100644
--- a/src/OpenFOAM/meshes/polyMesh/zones/zone/zone.C
+++ b/src/OpenFOAM/meshes/polyMesh/zones/zone/zone.C
@@ -63,14 +63,14 @@ void Foam::zone::calcLookupMap() const
             << abort(FatalError);
     }
 
-    const labelList& addr = *this;
+    const labelList& indices = *this;
 
-    lookupMapPtr_ = new Map<label>(2*addr.size());
+    lookupMapPtr_ = new Map<label>(2*indices.size());
     Map<label>& lm = *lookupMapPtr_;
 
-    forAll(addr, i)
+    forAll(indices, i)
     {
-        lm.insert(addr[i], i);
+        lm.insert(indices[i], i);
     }
 
     if (debug)
@@ -85,10 +85,10 @@ void Foam::zone::calcLookupMap() const
 Foam::zone::zone
 (
     const word& name,
-    const labelUList& addr
+    const labelUList& indices
 )
 :
-    labelList(addr),
+    labelList(indices),
     name_(name),
     lookupMapPtr_(nullptr)
 {}
@@ -97,10 +97,10 @@ Foam::zone::zone
 Foam::zone::zone
 (
     const word& name,
-    labelList&& addr
+    labelList&& indices
 )
 :
-    labelList(move(addr)),
+    labelList(move(indices)),
     name_(name),
     lookupMapPtr_(nullptr)
 {}
@@ -122,10 +122,10 @@ Foam::zone::zone
 Foam::zone::zone
 (
     const zone& z,
-    const labelUList& addr
+    const labelUList& indices
 )
 :
-    labelList(addr),
+    labelList(indices),
     name_(z.name()),
     lookupMapPtr_(nullptr)
 {}
@@ -134,10 +134,10 @@ Foam::zone::zone
 Foam::zone::zone
 (
     const zone& z,
-    labelList&& addr
+    labelList&& indices
 )
 :
-    labelList(move(addr)),
+    labelList(move(indices)),
     name_(z.name()),
     lookupMapPtr_(nullptr)
 {}
@@ -178,16 +178,16 @@ void Foam::zone::clearAddressing()
 
 bool Foam::zone::checkDefinition(const label maxSize, const bool report) const
 {
-    const labelList& addr = *this;
+    const labelList& indices = *this;
 
     bool hasError = false;
 
     // To check for duplicate entries
     labelHashSet elems(size());
 
-    forAll(addr, i)
+    forAll(indices, i)
     {
-        if (addr[i] < 0 || addr[i] >= maxSize)
+        if (indices[i] < 0 || indices[i] >= maxSize)
         {
             hasError = true;
 
@@ -195,7 +195,7 @@ bool Foam::zone::checkDefinition(const label maxSize, const bool report) const
             {
                 SeriousErrorInFunction
                     << "Zone " << name_
-                    << " contains invalid index label " << addr[i] << nl
+                    << " contains invalid index label " << indices[i] << nl
                     << "Valid index labels are 0.."
                     << maxSize-1 << endl;
             }
@@ -205,13 +205,13 @@ bool Foam::zone::checkDefinition(const label maxSize, const bool report) const
                 break;
             }
         }
-        else if (!elems.insert(addr[i]))
+        else if (!elems.insert(indices[i]))
         {
             if (report)
             {
                 WarningInFunction
                     << "Zone " << name_
-                    << " contains duplicate index label " << addr[i] << endl;
+                    << " contains duplicate index label " << indices[i] << endl;
             }
         }
     }
@@ -220,6 +220,14 @@ bool Foam::zone::checkDefinition(const label maxSize, const bool report) const
 }
 
 
+void Foam::zone::insert(const HashSet<label>& newIndices)
+{
+    HashSet<label> indices(*this);
+    indices.insert(newIndices);
+    labelList::operator=(indices.sortedToc());
+}
+
+
 void Foam::zone::topoChange(const polyTopoChangeMap& map)
 {
     clearAddressing();
@@ -261,17 +269,17 @@ void Foam::zone::operator=(zone&& zn)
 }
 
 
-void Foam::zone::operator=(const labelUList& addr)
+void Foam::zone::operator=(const labelUList& indices)
 {
     clearAddressing();
-    labelList::operator=(addr);
+    labelList::operator=(indices);
 }
 
 
-void Foam::zone::operator=(labelList&& addr)
+void Foam::zone::operator=(labelList&& indices)
 {
     clearAddressing();
-    labelList::operator=(move(addr));
+    labelList::operator=(move(indices));
 }
 
 
diff --git a/src/OpenFOAM/meshes/polyMesh/zones/zone/zone.H b/src/OpenFOAM/meshes/polyMesh/zones/zone/zone.H
index d89151aac2..60ba48501b 100644
--- a/src/OpenFOAM/meshes/polyMesh/zones/zone/zone.H
+++ b/src/OpenFOAM/meshes/polyMesh/zones/zone/zone.H
@@ -96,14 +96,14 @@ public:
         zone
         (
             const word& name,
-            const labelUList& addr
+            const labelUList& indices
         );
 
         //- Construct from components, moving contents
         zone
         (
             const word& name,
-            labelList&& addr
+            labelList&& indices
         );
 
         //- Construct from dictionary
@@ -119,7 +119,7 @@ public:
         zone
         (
             const zone&,
-            const labelUList& addr
+            const labelUList& indices
         );
 
         //- Construct given the original zone, resetting the
@@ -127,7 +127,7 @@ public:
         zone
         (
             const zone&,
-            labelList&& addr
+            labelList&& indices
         );
 
         //- Disallow default bitwise copy construction
@@ -167,6 +167,9 @@ public:
             const bool report = false
         ) const;
 
+        //- Insert given indices into zone
+        void insert(const HashSet<label>& newIndices);
+
         //- Correct patch after moving points
         virtual void movePoints(const pointField&)
         {}
@@ -195,10 +198,10 @@ public:
         //- Move assignment operator
         void operator=(zone&&);
 
-        //- Assignment operator to addressing
+        //- Assignment operator to indices
         void operator=(const labelUList&);
 
-        //- Move assignment of addressing
+        //- Move assignment of indices
         void operator=(labelList&&);
 
 
diff --git a/src/mesh/snappyHexMesh/meshRefinement/meshRefinementBaffles.C b/src/mesh/snappyHexMesh/meshRefinement/meshRefinementBaffles.C
index 6d0f9da5cd..a5fc203285 100644
--- a/src/mesh/snappyHexMesh/meshRefinement/meshRefinementBaffles.C
+++ b/src/mesh/snappyHexMesh/meshRefinement/meshRefinementBaffles.C
@@ -2997,6 +2997,24 @@ Foam::autoPtr<Foam::polyTopoChangeMap> Foam::meshRefinement::zonify
     }
 
 
+    // Put the cells into the correct zone
+    // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+    List<HashSet<label>> cellZoneNewCells(mesh_.cellZones().size());
+    forAll(cellToZone, celli)
+    {
+        const label zonei = cellToZone[celli];
+
+        if (zonei >= 0)
+        {
+            cellZoneNewCells[zonei].insert(celli);
+        }
+    }
+    forAll(cellZoneNewCells, zonei)
+    {
+        mesh_.cellZones()[zonei].insert(cellZoneNewCells[zonei]);
+    }
+
+
     // Topochange container
     polyTopoChange meshMod(mesh_);
 
@@ -3154,7 +3172,6 @@ Foam::autoPtr<Foam::polyTopoChangeMap> Foam::meshRefinement::zonify
         }
     }
 
-
     // Put the faces into the correct zone
     // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -3250,20 +3267,6 @@ Foam::autoPtr<Foam::polyTopoChangeMap> Foam::meshRefinement::zonify
         }
     }
 
-
-    // Put the cells into the correct zone
-    // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-    forAll(cellToZone, celli)
-    {
-        const label zonei = cellToZone[celli];
-
-        if (zonei >= 0)
-        {
-            meshMod.modifyCell(celli, zonei);
-        }
-    }
-
     mesh_.clearOut();
 
     // Change the mesh without keeping old points, parallel sync
diff --git a/src/polyTopoChange/polyTopoChange/polyTopoChange.C b/src/polyTopoChange/polyTopoChange/polyTopoChange.C
index 694e06fd32..621a55f328 100644
--- a/src/polyTopoChange/polyTopoChange/polyTopoChange.C
+++ b/src/polyTopoChange/polyTopoChange/polyTopoChange.C
@@ -2491,16 +2491,6 @@ Foam::label Foam::polyTopoChange::addCell
 }
 
 
-void Foam::polyTopoChange::modifyCell
-(
-    const label celli,
-    const label zoneID
-)
-{
-    cellZone_[celli] = zoneID;
-}
-
-
 void Foam::polyTopoChange::removeCell(const label celli, const label mergeCelli)
 {
     if (celli < 0 || celli >= cellMap_.size())
diff --git a/src/polyTopoChange/polyTopoChange/polyTopoChange.H b/src/polyTopoChange/polyTopoChange/polyTopoChange.H
index 5f72bc6aaa..22d0d9bcaa 100644
--- a/src/polyTopoChange/polyTopoChange/polyTopoChange.H
+++ b/src/polyTopoChange/polyTopoChange/polyTopoChange.H
@@ -533,9 +533,6 @@ public:
                 const label zoneID
             );
 
-            //- Modify zone of cell
-            void modifyCell(const label, const label zoneID);
-
             //- Remove/merge cell.
             void removeCell(const label, const label);
 
diff --git a/tutorials/multicomponentFluid/membrane/system/controlDict b/tutorials/multicomponentFluid/membrane/system/controlDict
index 7dbaff70db..0d9caddff3 100644
--- a/tutorials/multicomponentFluid/membrane/system/controlDict
+++ b/tutorials/multicomponentFluid/membrane/system/controlDict
@@ -34,7 +34,7 @@ writeInterval   0.1;
 
 purgeWrite      0;
 
-writeFormat     binary;
+writeFormat     ascii;
 
 writePrecision  6;