diff --git a/src/OSspecific/POSIX/signals/sigStopAtWriteNow.C b/src/OSspecific/POSIX/signals/sigStopAtWriteNow.C
index 6d55136a2d1dbbf1cf4cc019afd7c5531e0ed72e..7dc579f1ea6205c6dda670e00482b4c6054ad324 100644
--- a/src/OSspecific/POSIX/signals/sigStopAtWriteNow.C
+++ b/src/OSspecific/POSIX/signals/sigStopAtWriteNow.C
@@ -53,10 +53,12 @@ static Foam::Time const* runTimePtr_ = nullptr;
 namespace Foam
 {
 // Register re-reader
-struct addstopAtWriteNowSignalToOpt
+class addstopAtWriteNowSignalToOpt
 :
     public ::Foam::simpleRegIOobject
 {
+public:
+
     addstopAtWriteNowSignalToOpt(const char* name)
     :
         ::Foam::simpleRegIOobject(Foam::debug::addOptimisationObject, name)
diff --git a/src/OSspecific/POSIX/signals/sigWriteNow.C b/src/OSspecific/POSIX/signals/sigWriteNow.C
index 71d309adc5d562a16a99717858cbe1d4afab15c1..6ba56c23ceb744953eca48f012e5fd84fc500d2d 100644
--- a/src/OSspecific/POSIX/signals/sigWriteNow.C
+++ b/src/OSspecific/POSIX/signals/sigWriteNow.C
@@ -53,10 +53,12 @@ namespace Foam
 {
 
 // Register re-reader
-struct addwriteNowSignalToOpt
+class addwriteNowSignalToOpt
 :
     public ::Foam::simpleRegIOobject
 {
+public:
+
     addwriteNowSignalToOpt(const char* name)
     :
         ::Foam::simpleRegIOobject(Foam::debug::addOptimisationObject, name)
diff --git a/src/conversion/vtk/adaptor/foamVtkVtuAdaptor.H b/src/conversion/vtk/adaptor/foamVtkVtuAdaptor.H
index 4d3e74177f7f6c7fc307fc8407bc19970909cf56..bce4b42cd9d57920ce3a1770be1730cddc654e15 100644
--- a/src/conversion/vtk/adaptor/foamVtkVtuAdaptor.H
+++ b/src/conversion/vtk/adaptor/foamVtkVtuAdaptor.H
@@ -74,11 +74,13 @@ namespace vtk
 \*---------------------------------------------------------------------------*/
 
 //- Bookkeeping for vtkUnstructuredGrid
-struct vtuAdaptor
+class vtuAdaptor
 :
     public vtk::Caching<vtkUnstructuredGrid>,
     public foamVtkMeshMaps
 {
+public:
+
     // Member Functions
 
     // Mesh Conversion