diff --git a/applications/utilities/postProcessing/dataConversion/foamToVTK/convertVolumeFields.H b/applications/utilities/postProcessing/dataConversion/foamToVTK/convertVolumeFields.H
index 150e19f45e..629ca24911 100644
--- a/applications/utilities/postProcessing/dataConversion/foamToVTK/convertVolumeFields.H
+++ b/applications/utilities/postProcessing/dataConversion/foamToVTK/convertVolumeFields.H
@@ -368,11 +368,7 @@ Description
         {
             const label nPatchFields =
             (
-                (
-                    writeri < patchInterps.size() && patchInterps.set(writeri)
-                  ? nVolFields
-                  : 0
-                )
+                (patchInterps.test(writeri) ? nVolFields : 0)
               + nPointFields
             );
 
diff --git a/applications/utilities/postProcessing/dataConversion/foamToVTK/writeVolFields.H b/applications/utilities/postProcessing/dataConversion/foamToVTK/writeVolFields.H
index 8a04c3ddf4..bd415eaf5d 100644
--- a/applications/utilities/postProcessing/dataConversion/foamToVTK/writeVolFields.H
+++ b/applications/utilities/postProcessing/dataConversion/foamToVTK/writeVolFields.H
@@ -116,7 +116,7 @@ label writeVolFields
             label writeri = 0;
             for (vtk::patchWriter& writer : patchWriters)
             {
-                if (writeri < patchInterps.size() && patchInterps.set(writeri))
+                if (patchInterps.test(writeri))
                 {
                     writer.write(tfield(), patchInterps[writeri]);
                 }
diff --git a/src/dynamicMesh/fvMeshAdder/fvMeshAdderTemplates.C b/src/dynamicMesh/fvMeshAdder/fvMeshAdderTemplates.C
index dd5d7b357e..3353037b84 100644
--- a/src/dynamicMesh/fvMeshAdder/fvMeshAdderTemplates.C
+++ b/src/dynamicMesh/fvMeshAdder/fvMeshAdderTemplates.C
@@ -712,15 +712,12 @@ void Foam::fvMeshAdder::MapDimField
     // Add fields to fields[0] after adding the meshes to meshes[0].
     // Mesh[0] is the sum of all meshes. Fields are not yet mapped.
 
-    if
-    (
-        flds.size() == 0
-    || !flds.set(0)
-    || cellProcAddressing.size() != flds.size()
-    )
+    if (!flds.test(0) || cellProcAddressing.size() != flds.size())
     {
-        FatalErrorInFunction << "Not valid field at element 0"
-            << " in field list of size " << flds.size() << exit(FatalError);
+        FatalErrorInFunction
+            << "Not valid field at element 0 in list of size "
+            << flds.size() << nl
+            << exit(FatalError);
     }
 
 
@@ -766,10 +763,12 @@ void Foam::fvMeshAdder::MapVolField
     // Add fields to fields[0] after adding the meshes to meshes[0].
     // Mesh[0] is the sum of all meshes. Fields are not yet mapped.
 
-    if (flds.size() == 0 || !flds.set(0))
+    if (!flds.test(0))
     {
-        FatalErrorInFunction << "Not valid field at element 0"
-            << " in field list of size " << flds.size() << exit(FatalError);
+        FatalErrorInFunction
+            << "Not valid field at element 0 in list of size "
+            << flds.size() << nl
+            << exit(FatalError);
     }
 
 
@@ -902,10 +901,12 @@ void Foam::fvMeshAdder::MapSurfaceField
     // Add fields to fields[0] after adding the meshes to meshes[0].
     // Mesh[0] is the sum of all meshes. Fields are not yet mapped.
 
-    if (flds.size() == 0 || !flds.set(0))
+    if (!flds.test(0))
     {
-        FatalErrorInFunction << "Not valid field at element 0"
-            << " in field list of size " << flds.size() << exit(FatalError);
+        FatalErrorInFunction
+            << "Not valid field at element 0 in list of size "
+            << flds.size() << nl
+            << exit(FatalError);
     }
 
     const fvMesh& mesh0 = flds[0].mesh();
@@ -1105,12 +1106,14 @@ void Foam::fvMeshAdder::MapVolFields
 {
     typedef GeometricField<Type, fvPatchField, volMesh> fldType;
 
-    if (meshes.size() == 0 || !meshes.set(0))
+    if (!meshes.test(0))
     {
-        FatalErrorInFunction << "Not valid field at element 0"
-            << " in mesh list of size " << meshes.size() << exit(FatalError);
+        FatalErrorInFunction
+            << "Not valid mesh at element 0 in list of size "
+            << meshes.size() << nl
+            << exit(FatalError);
     }
-    const fvMesh& mesh0 = meshes[0];
+    const auto& mesh0 = meshes[0];
 
     HashTable<const fldType*> fields
     (
@@ -1176,12 +1179,14 @@ void Foam::fvMeshAdder::MapDimFields
     typedef DimensionedField<Type, volMesh> fldType;
     typedef GeometricField<Type, fvPatchField, volMesh> excludeType;
 
-    if (meshes.size() == 0 || !meshes.set(0))
+    if (!meshes.test(0))
     {
-        FatalErrorInFunction << "Not valid field at element 0"
-            << " in mesh list of size " << meshes.size() << exit(FatalError);
+        FatalErrorInFunction
+            << "Not valid mesh at element 0 in list of size "
+            << meshes.size() << nl
+            << exit(FatalError);
     }
-    const fvMesh& mesh0 = meshes[0];
+    const auto& mesh0 = meshes[0];
 
     HashTable<const fldType*> fields
     (
@@ -1236,10 +1241,12 @@ void Foam::fvMeshAdder::MapSurfaceFields
 {
     typedef GeometricField<Type, fvsPatchField, surfaceMesh> fldType;
 
-    if (meshes.size() == 0 || !meshes.set(0))
+    if (!meshes.test(0))
     {
-        FatalErrorInFunction << "Not valid field at element 0"
-            << " in mesh list of size " << meshes.size() << exit(FatalError);
+        FatalErrorInFunction
+            << "Not valid mesh at element 0 in list of size "
+            << meshes.size() << nl
+            << exit(FatalError);
     }
     const auto& mesh0 = meshes[0];
 
diff --git a/src/functionObjects/utilities/vtkWrite/vtkWrite.C b/src/functionObjects/utilities/vtkWrite/vtkWrite.C
index 0b38881561..f8e3afc33f 100644
--- a/src/functionObjects/utilities/vtkWrite/vtkWrite.C
+++ b/src/functionObjects/utilities/vtkWrite/vtkWrite.C
@@ -627,9 +627,7 @@ bool Foam::functionObjects::vtkWrite::write()
             {
                 const label nPatchFields =
                 (
-                    writeri < patchInterps.size() && patchInterps.set(writeri)
-                  ? nVolFields
-                  : 0
+                    patchInterps.test(writeri) ? nVolFields : 0
                 );
 
                 if (nPatchFields)
diff --git a/src/functionObjects/utilities/vtkWrite/vtkWriteImpl.C b/src/functionObjects/utilities/vtkWrite/vtkWriteImpl.C
index 66400af4be..9d3c60ac3e 100644
--- a/src/functionObjects/utilities/vtkWrite/vtkWriteImpl.C
+++ b/src/functionObjects/utilities/vtkWrite/vtkWriteImpl.C
@@ -128,7 +128,7 @@ Foam::label Foam::functionObjects::vtkWrite::writeVolFieldsImpl
         label writeri = 0;
         for (vtk::patchWriter& writer : patchWriters)
         {
-            if (writeri < patchInterps.size() && patchInterps.set(writeri))
+            if (patchInterps.test(writeri))
             {
                 ok = true;
                 writer.write(field, patchInterps[writeri]);