diff --git a/src/OpenMesh/Core/IO/writer/BaseWriter.hh b/src/OpenMesh/Core/IO/writer/BaseWriter.hh
index f23d2783..d45bbee1 100644
--- a/src/OpenMesh/Core/IO/writer/BaseWriter.hh
+++ b/src/OpenMesh/Core/IO/writer/BaseWriter.hh
@@ -125,21 +125,21 @@ public:
                      std::streamsize _precision = 6) const = 0;
 
   /// Returns expected size of file if binary format is supported else 0.
-  virtual size_t binary_size(BaseExporter&, Options) const { return 0; }
+  virtual size_t binary_size(BaseExporter&, const Options&) const { return 0; }
 
 
 
 protected:
 
-  bool check(BaseExporter& _be, Options _opt) const
+  bool check(BaseExporter& _be, const Options& _writeOptions) const
   {
     // Check for all Options. When we want to write them (_opt.check() ) , they have to be available ( has_ )
     // Converts to not A (write them) or B (available)
-    return     ( !_opt.check(Options::VertexNormal ) || _be.has_vertex_normals())
-           &&  ( !_opt.check(Options::VertexTexCoord)|| _be.has_vertex_texcoords())
-           &&  ( !_opt.check(Options::VertexColor)   || _be.has_vertex_colors())
-           &&  ( !_opt.check(Options::FaceNormal)    || _be.has_face_normals())
-           &&  ( !_opt.check(Options::FaceColor)     || _be.has_face_colors());
+    return     ( !_writeOptions.check(Options::VertexNormal ) || _be.has_vertex_normals())
+           &&  ( !_writeOptions.check(Options::VertexTexCoord)|| _be.has_vertex_texcoords())
+           &&  ( !_writeOptions.check(Options::VertexColor)   || _be.has_vertex_colors())
+           &&  ( !_writeOptions.check(Options::FaceNormal)    || _be.has_face_normals())
+           &&  ( !_writeOptions.check(Options::FaceColor)     || _be.has_face_colors());
   }
 };
 
diff --git a/src/OpenMesh/Core/IO/writer/OBJWriter.hh b/src/OpenMesh/Core/IO/writer/OBJWriter.hh
index f667b1a9..a8a6cc98 100644
--- a/src/OpenMesh/Core/IO/writer/OBJWriter.hh
+++ b/src/OpenMesh/Core/IO/writer/OBJWriter.hh
@@ -95,7 +95,7 @@ public:
 
   bool write(std::ostream&, BaseExporter&, const Options& _writeOptions, std::streamsize _precision = 6) const override;
 
-  size_t binary_size(BaseExporter&, Options) const override { return 0; }
+  size_t binary_size(BaseExporter&, const Options&) const override { return 0; }
 
 private:
 
diff --git a/src/OpenMesh/Core/IO/writer/OFFWriter.cc b/src/OpenMesh/Core/IO/writer/OFFWriter.cc
index aeb933dc..0dbee223 100644
--- a/src/OpenMesh/Core/IO/writer/OFFWriter.cc
+++ b/src/OpenMesh/Core/IO/writer/OFFWriter.cc
@@ -136,7 +136,7 @@ write(std::ostream& _os, BaseExporter& _be, const Options& _writeOptions, std::s
 
 bool
 _OFFWriter_::
-write_ascii(std::ostream& _out, BaseExporter& _be, Options _opt) const
+write_ascii(std::ostream& _out, BaseExporter& _be, const Options& _writeOptions) const
 {
 
   unsigned int i, nV, nF;
@@ -155,7 +155,7 @@ write_ascii(std::ostream& _out, BaseExporter& _be, Options _opt) const
   _out << _be.n_faces() << " ";
   _out << 0 << "\n";
 
-  if (_opt.color_is_float())
+  if (_writeOptions.color_is_float())
     _out << std::fixed;
 
 
@@ -169,16 +169,16 @@ write_ascii(std::ostream& _out, BaseExporter& _be, Options _opt) const
     _out << v[0] << " " << v[1] << " " << v[2];
 
     // VertexNormal
-    if ( _opt.vertex_has_normal() ) {
+    if ( _writeOptions.vertex_has_normal() ) {
       n  = _be.normal(vh);
       _out << " " << n[0] << " " << n[1] << " " << n[2];
     }
 
     // VertexColor
-    if ( _opt.vertex_has_color() ) {
-      if ( _opt.color_is_float() ) {
+    if ( _writeOptions.vertex_has_color() ) {
+      if ( _writeOptions.color_is_float() ) {
         //with alpha
-        if ( _opt.color_has_alpha() ){
+        if ( _writeOptions.color_has_alpha() ){
           cAf  = _be.colorAf(vh);
           _out << " " << cAf;
         }else{
@@ -188,7 +188,7 @@ write_ascii(std::ostream& _out, BaseExporter& _be, Options _opt) const
         }
       } else {
         //with alpha
-        if ( _opt.color_has_alpha() ){
+        if ( _writeOptions.color_has_alpha() ){
           cA  = _be.colorA(vh);
           _out << " " << cA;
         }else{
@@ -200,7 +200,7 @@ write_ascii(std::ostream& _out, BaseExporter& _be, Options _opt) const
     }
 
     // TexCoord
-    if (_opt.vertex_has_texcoord() ) {
+    if (_writeOptions.vertex_has_texcoord() ) {
       t  = _be.texcoord(vh);
       _out << " " << t[0] << " " << t[1];
     }
@@ -221,10 +221,10 @@ write_ascii(std::ostream& _out, BaseExporter& _be, Options _opt) const
       _out << vhandles[2].idx();
 
       //face color
-      if ( _opt.face_has_color() ){
-        if ( _opt.color_is_float() ) {
+      if ( _writeOptions.face_has_color() ){
+        if ( _writeOptions.color_is_float() ) {
           //with alpha
-          if ( _opt.color_has_alpha() ){
+          if ( _writeOptions.color_has_alpha() ){
             cAf  = _be.colorAf( FaceHandle(i) );
             _out << " " << cAf;
           }else{
@@ -234,7 +234,7 @@ write_ascii(std::ostream& _out, BaseExporter& _be, Options _opt) const
           }
         } else {
           //with alpha
-          if ( _opt.color_has_alpha() ){
+          if ( _writeOptions.color_has_alpha() ){
             cA  = _be.colorA( FaceHandle(i) );
             _out << " " << cA;
           }else{
@@ -257,10 +257,10 @@ write_ascii(std::ostream& _out, BaseExporter& _be, Options _opt) const
 	       _out << vhandles[j].idx() << " ";
 
       //face color
-      if ( _opt.face_has_color() ){
-        if ( _opt.color_is_float() ) {
+      if ( _writeOptions.face_has_color() ){
+        if ( _writeOptions.color_is_float() ) {
           //with alpha
-          if ( _opt.color_has_alpha() ){
+          if ( _writeOptions.color_has_alpha() ){
             cAf  = _be.colorAf( FaceHandle(i) );
             _out << " " << cAf;
           }else{
@@ -270,7 +270,7 @@ write_ascii(std::ostream& _out, BaseExporter& _be, Options _opt) const
           }
         } else {
           //with alpha
-          if ( _opt.color_has_alpha() ){
+          if ( _writeOptions.color_has_alpha() ){
             cA  = _be.colorA( FaceHandle(i) );
             _out << " " << cA;
           }else{
@@ -312,7 +312,7 @@ void _OFFWriter_::writeValue(std::ostream& _out, float value) const {
 
 bool
 _OFFWriter_::
-write_binary(std::ostream& _out, BaseExporter& _be, Options _opt) const
+write_binary(std::ostream& _out, BaseExporter& _be, const Options& _writeOptions) const
 {
 
   unsigned int i, nV, nF;
@@ -340,21 +340,21 @@ write_binary(std::ostream& _out, BaseExporter& _be, Options _opt) const
     writeValue(_out, v[2]);
 
     // vertex normal
-    if ( _opt.vertex_has_normal() ) {
+    if ( _writeOptions.vertex_has_normal() ) {
       n  = _be.normal(vh);
       writeValue(_out, n[0]);
       writeValue(_out, n[1]);
       writeValue(_out, n[2]);
     }
     // vertex color
-    if ( _opt.vertex_has_color() ) {
-      if ( _opt.color_is_float() ) {
+    if ( _writeOptions.vertex_has_color() ) {
+      if ( _writeOptions.color_is_float() ) {
         cf  = _be.colorAf(vh);
         writeValue(_out, cf[0]);
         writeValue(_out, cf[1]);
         writeValue(_out, cf[2]);
 
-        if ( _opt.color_has_alpha() )
+        if ( _writeOptions.color_has_alpha() )
           writeValue(_out, cf[3]);
       } else {
         c  = _be.colorA(vh);
@@ -362,12 +362,12 @@ write_binary(std::ostream& _out, BaseExporter& _be, Options _opt) const
         writeValue(_out, c[1]);
         writeValue(_out, c[2]);
 
-        if ( _opt.color_has_alpha() )
+        if ( _writeOptions.color_has_alpha() )
           writeValue(_out, c[3]);
       }
     }
     // texCoords
-    if (_opt.vertex_has_texcoord() ) {
+    if (_writeOptions.vertex_has_texcoord() ) {
       t  = _be.texcoord(vh);
       writeValue(_out, t[0]);
       writeValue(_out, t[1]);
@@ -388,14 +388,14 @@ write_binary(std::ostream& _out, BaseExporter& _be, Options _opt) const
       writeValue(_out, vhandles[2].idx());
 
       //face color
-      if ( _opt.face_has_color() ){
-        if ( _opt.color_is_float() ) {
+      if ( _writeOptions.face_has_color() ){
+        if ( _writeOptions.color_is_float() ) {
           cf  = _be.colorAf( FaceHandle(i) );
           writeValue(_out, cf[0]);
           writeValue(_out, cf[1]);
           writeValue(_out, cf[2]);
 
-          if ( _opt.color_has_alpha() )
+          if ( _writeOptions.color_has_alpha() )
             writeValue(_out, cf[3]);
         } else {
           c  = _be.colorA( FaceHandle(i) );
@@ -403,7 +403,7 @@ write_binary(std::ostream& _out, BaseExporter& _be, Options _opt) const
           writeValue(_out, c[1]);
           writeValue(_out, c[2]);
 
-          if ( _opt.color_has_alpha() )
+          if ( _writeOptions.color_has_alpha() )
             writeValue(_out, c[3]);
         }
       }
@@ -420,14 +420,14 @@ write_binary(std::ostream& _out, BaseExporter& _be, Options _opt) const
         writeValue(_out, vhandles[j].idx() );
 
       //face color
-      if ( _opt.face_has_color() ){
-        if ( _opt.color_is_float() ) {
+      if ( _writeOptions.face_has_color() ){
+        if ( _writeOptions.color_is_float() ) {
           cf  = _be.colorAf( FaceHandle(i) );
           writeValue(_out, cf[0]);
           writeValue(_out, cf[1]);
           writeValue(_out, cf[2]);
 
-          if ( _opt.color_has_alpha() )
+          if ( _writeOptions.color_has_alpha() )
             writeValue(_out, cf[3]);
         } else {
           c  = _be.colorA( FaceHandle(i) );
@@ -435,7 +435,7 @@ write_binary(std::ostream& _out, BaseExporter& _be, Options _opt) const
           writeValue(_out, c[1]);
           writeValue(_out, c[2]);
 
-          if ( _opt.color_has_alpha() )
+          if ( _writeOptions.color_has_alpha() )
             writeValue(_out, c[3]);
         }
       }
@@ -450,7 +450,7 @@ write_binary(std::ostream& _out, BaseExporter& _be, Options _opt) const
 
 size_t
 _OFFWriter_::
-binary_size(BaseExporter& _be, Options _opt) const
+binary_size(BaseExporter& _be, const Options& _writeOptions) const
 {
   size_t header(0);
   size_t data(0);
@@ -459,7 +459,7 @@ binary_size(BaseExporter& _be, Options _opt) const
   size_t _3ui(3*sizeof(unsigned int));
   size_t _4ui(4*sizeof(unsigned int));
 
-  if ( !_opt.is_binary() )
+  if ( !_writeOptions.is_binary() )
     return 0;
   else
   {
@@ -470,19 +470,19 @@ binary_size(BaseExporter& _be, Options _opt) const
     data   += _be.n_vertices() * _3floats;    // vertex data
   }
 
-  if ( _opt.vertex_has_normal() && _be.has_vertex_normals() )
+  if ( _writeOptions.vertex_has_normal() && _be.has_vertex_normals() )
   {
     header += 1; // N
     data   += _be.n_vertices() * _3floats;
   }
 
-  if ( _opt.vertex_has_color() && _be.has_vertex_colors() )
+  if ( _writeOptions.vertex_has_color() && _be.has_vertex_colors() )
   {
     header += 1; // C
     data   += _be.n_vertices() * _3floats;
   }
 
-  if ( _opt.vertex_has_texcoord() && _be.has_vertex_texcoords() )
+  if ( _writeOptions.vertex_has_texcoord() && _be.has_vertex_texcoords() )
   {
     size_t _2floats(2*sizeof(float));
     header += 2; // ST
@@ -505,8 +505,8 @@ binary_size(BaseExporter& _be, Options _opt) const
   }
 
   // face colors
-  if ( _opt.face_has_color() && _be.has_face_colors() ){
-    if ( _opt.color_has_alpha() )
+  if ( _writeOptions.face_has_color() && _be.has_face_colors() ){
+    if ( _writeOptions.color_has_alpha() )
       data += _be.n_faces() * _4ui;
     else
       data += _be.n_faces() * _3ui;
diff --git a/src/OpenMesh/Core/IO/writer/OFFWriter.hh b/src/OpenMesh/Core/IO/writer/OFFWriter.hh
index 7458c1ae..4bea49b1 100644
--- a/src/OpenMesh/Core/IO/writer/OFFWriter.hh
+++ b/src/OpenMesh/Core/IO/writer/OFFWriter.hh
@@ -104,7 +104,7 @@ public:
 
   bool write(std::ostream&, BaseExporter&, const Options& _writeOptions, std::streamsize _precision = 6) const override;
 
-  size_t binary_size(BaseExporter& _be, Options _opt) const override;
+  size_t binary_size(BaseExporter& _be, const Options& _opt) const override;
 
 
 protected:
@@ -112,8 +112,8 @@ protected:
   void writeValue(std::ostream& _out, unsigned int value) const;
   void writeValue(std::ostream& _out, float value) const;
 
-  bool write_ascii(std::ostream& _in, BaseExporter&, Options) const;
-  bool write_binary(std::ostream& _in, BaseExporter&, Options) const;
+  bool write_ascii(std::ostream& _in, BaseExporter&, const Options& _writeOptions) const;
+  bool write_binary(std::ostream& _in, BaseExporter&, const Options& _writeOptions) const;
 };
 
 
diff --git a/src/OpenMesh/Core/IO/writer/OMWriter.cc b/src/OpenMesh/Core/IO/writer/OMWriter.cc
index 11939ea5..7221c0b4 100644
--- a/src/OpenMesh/Core/IO/writer/OMWriter.cc
+++ b/src/OpenMesh/Core/IO/writer/OMWriter.cc
@@ -175,7 +175,7 @@ template <typename T> struct Enabler
 
 
 bool _OMWriter_::write_binary(std::ostream& _os, BaseExporter& _be,
-                               Options _opt) const
+                               const Options& _writeOptions) const
 {
   #ifndef DOXY_IGNORE_THIS
     Enabler<mostream> enabler(omlog());
@@ -184,7 +184,7 @@ bool _OMWriter_::write_binary(std::ostream& _os, BaseExporter& _be,
   size_t bytes = 0;
 
   const bool swap =
-      _opt.check(Options::Swap) || (Endian::local() == Endian::MSB);
+      _writeOptions.check(Options::Swap) || (Endian::local() == Endian::MSB);
 
   unsigned int i, nV, nF;
   Vec3f v;
@@ -245,7 +245,7 @@ bool _OMWriter_::write_binary(std::ostream& _os, BaseExporter& _be,
 
 
   // ---------- write vertex normal
-  if (_be.n_vertices() && _opt.check( Options::VertexNormal ))
+  if (_be.n_vertices() && _writeOptions.check( Options::VertexNormal ))
   {
     Vec3f n = _be.normal(VertexHandle(0));
     Vec3d nd = _be.normald(VertexHandle(0));
@@ -279,7 +279,7 @@ bool _OMWriter_::write_binary(std::ostream& _os, BaseExporter& _be,
   }
 
   // ---------- write vertex color
-  if (_be.n_vertices() && _opt.check( Options::VertexColor ) && _be.has_vertex_colors() )
+  if (_be.n_vertices() && _writeOptions.check( Options::VertexColor ) && _be.has_vertex_colors() )
   {
     Vec3uc c = _be.color(VertexHandle(0));
 
@@ -297,7 +297,7 @@ bool _OMWriter_::write_binary(std::ostream& _os, BaseExporter& _be,
   }
 
   // ---------- write vertex texture coords
-  if (_be.n_vertices() && _opt.check(Options::VertexTexCoord)) {
+  if (_be.n_vertices() && _writeOptions.check(Options::VertexTexCoord)) {
 
     t = _be.texcoord(VertexHandle(0));
 
@@ -344,7 +344,7 @@ bool _OMWriter_::write_binary(std::ostream& _os, BaseExporter& _be,
 
 
   // ---------- write face texture coords
-  if (_OMWriter_::version_ > OMFormat::mk_version(2,1) && _be.n_edges() && _opt.check(Options::FaceTexCoord))
+  if (_OMWriter_::version_ > OMFormat::mk_version(2,1) && _be.n_edges() && _writeOptions.check(Options::FaceTexCoord))
   {
 
     t = _be.texcoord(HalfedgeHandle(0));
@@ -407,7 +407,7 @@ bool _OMWriter_::write_binary(std::ostream& _os, BaseExporter& _be,
 
   // ---------- write face normals
 
-  if (_be.n_faces() && _be.has_face_normals() && _opt.check(Options::FaceNormal) )
+  if (_be.n_faces() && _be.has_face_normals() && _writeOptions.check(Options::FaceNormal) )
   {
 #define NEW_STYLE 0
 #if NEW_STYLE
@@ -459,7 +459,7 @@ bool _OMWriter_::write_binary(std::ostream& _os, BaseExporter& _be,
 
   // ---------- write face color
 
-  if (_be.n_faces() && _be.has_face_colors() && _opt.check( Options::FaceColor ))
+  if (_be.n_faces() && _be.has_face_colors() && _writeOptions.check( Options::FaceColor ))
   {
 #define NEW_STYLE 0
 #if NEW_STYLE
@@ -491,7 +491,7 @@ bool _OMWriter_::write_binary(std::ostream& _os, BaseExporter& _be,
   }
 
   // ---------- write vertex status
-  if (_be.n_vertices() && _be.has_vertex_status() && _opt.check(Options::Status))
+  if (_be.n_vertices() && _be.has_vertex_status() && _writeOptions.check(Options::Status))
   {
     auto s = _be.status(VertexHandle(0));
     chunk_header.name_ = false;
@@ -510,7 +510,7 @@ bool _OMWriter_::write_binary(std::ostream& _os, BaseExporter& _be,
   }
 
   // ---------- write edge status
-  if (_be.n_edges() && _be.has_edge_status() && _opt.check(Options::Status))
+  if (_be.n_edges() && _be.has_edge_status() && _writeOptions.check(Options::Status))
   {
     auto s = _be.status(EdgeHandle(0));
     chunk_header.name_ = false;
@@ -529,7 +529,7 @@ bool _OMWriter_::write_binary(std::ostream& _os, BaseExporter& _be,
   }
 
   // ---------- write halfedge status
-  if (_be.n_edges() && _be.has_halfedge_status() && _opt.check(Options::Status))
+  if (_be.n_edges() && _be.has_halfedge_status() && _writeOptions.check(Options::Status))
   {
     auto s = _be.status(HalfedgeHandle(0));
     chunk_header.name_ = false;
@@ -548,7 +548,7 @@ bool _OMWriter_::write_binary(std::ostream& _os, BaseExporter& _be,
   }
 
   // ---------- write face status
-  if (_be.n_faces() && _be.has_face_status() && _opt.check(Options::Status))
+  if (_be.n_faces() && _be.has_face_status() && _writeOptions.check(Options::Status))
   {
     auto s = _be.status(FaceHandle(0));
     chunk_header.name_ = false;
@@ -568,7 +568,7 @@ bool _OMWriter_::write_binary(std::ostream& _os, BaseExporter& _be,
 
   // -------------------- write custom properties
 
-  if (_opt.check(Options::Custom))
+  if (_writeOptions.check(Options::Custom))
   {
     const auto store_property = [this, &_os, swap, &bytes](
       const BaseKernel::const_prop_iterator _it_begin,
@@ -672,7 +672,7 @@ size_t _OMWriter_::store_binary_custom_chunk(std::ostream& _os,
 
 // ----------------------------------------------------------------------------
 
-size_t _OMWriter_::binary_size(BaseExporter& /* _be */, Options /* _opt */) const
+size_t _OMWriter_::binary_size(BaseExporter& /* _be */, const Options& /* _opt */) const
 {
   // std::clog << "[OMWriter]: binary_size()" << std::endl;
   size_t bytes  = sizeof( OMFormat::Header );
diff --git a/src/OpenMesh/Core/IO/writer/OMWriter.hh b/src/OpenMesh/Core/IO/writer/OMWriter.hh
index 60fd79db..4476d456 100644
--- a/src/OpenMesh/Core/IO/writer/OMWriter.hh
+++ b/src/OpenMesh/Core/IO/writer/OMWriter.hh
@@ -106,7 +106,7 @@ public:
 
   bool write(std::ostream&, BaseExporter&, const Options& _writeOptions, std::streamsize _precision = 6) const override;
 
-  size_t binary_size(BaseExporter& _be, Options _opt) const override;
+  size_t binary_size(BaseExporter& _be, const Options& _opt) const override;
 
   static OMFormat::uint8 get_version() { return version_; }
 
@@ -116,9 +116,9 @@ protected:
   static const OMFormat::uchar magic_[3];
   static const OMFormat::uint8 version_;
 
-  bool write(const std::string&, BaseExporter&, const Options&, std::streamsize _precision = 6) const override;
+  bool write(const std::string&, BaseExporter&, const Options& _writeOptions, std::streamsize _precision = 6) const override;
 
-  bool write_binary(std::ostream&, BaseExporter&, Options) const;
+  bool write_binary(std::ostream&, BaseExporter&, const Options& _writeOptions) const;
 
 
   size_t store_binary_custom_chunk(std::ostream&, BaseProperty&,
diff --git a/src/OpenMesh/Core/IO/writer/PLYWriter.cc b/src/OpenMesh/Core/IO/writer/PLYWriter.cc
index b5cc6f35..bb133dbf 100644
--- a/src/OpenMesh/Core/IO/writer/PLYWriter.cc
+++ b/src/OpenMesh/Core/IO/writer/PLYWriter.cc
@@ -708,7 +708,7 @@ write_binary(std::ostream& _out, BaseExporter& _be, Options _opt) const
 
 size_t
 _PLYWriter_::
-binary_size(BaseExporter& _be, Options _opt) const
+binary_size(BaseExporter& _be, const Options& _writeOptions) const
 {
   size_t header(0);
   size_t data(0);
@@ -716,7 +716,7 @@ binary_size(BaseExporter& _be, Options _opt) const
   size_t _3ui(3*sizeof(unsigned int));
   size_t _4ui(4*sizeof(unsigned int));
 
-  if ( !_opt.is_binary() )
+  if ( !_writeOptions.is_binary() )
     return 0;
   else
   {
@@ -728,19 +728,19 @@ binary_size(BaseExporter& _be, Options _opt) const
     data   += _be.n_vertices() * _3floats;    // vertex data
   }
 
-  if ( _opt.vertex_has_normal() && _be.has_vertex_normals() )
+  if ( _writeOptions.vertex_has_normal() && _be.has_vertex_normals() )
   {
     header += 1; // N
     data   += _be.n_vertices() * _3floats;
   }
 
-  if ( _opt.vertex_has_color() && _be.has_vertex_colors() )
+  if ( _writeOptions.vertex_has_color() && _be.has_vertex_colors() )
   {
     header += 1; // C
     data   += _be.n_vertices() * _3floats;
   }
 
-  if ( _opt.vertex_has_texcoord() && _be.has_vertex_texcoords() )
+  if ( _writeOptions.vertex_has_texcoord() && _be.has_vertex_texcoords() )
   {
     size_t _2floats(2*sizeof(float));
     header += 2; // ST
@@ -765,8 +765,8 @@ binary_size(BaseExporter& _be, Options _opt) const
   }
 
   // face colors
-  if ( _opt.face_has_color() && _be.has_face_colors() ){
-    if ( _opt.color_has_alpha() )
+  if ( _writeOptions.face_has_color() && _be.has_face_colors() ){
+    if ( _writeOptions.color_has_alpha() )
       data += _be.n_faces() * _4ui;
     else
       data += _be.n_faces() * _3ui;
diff --git a/src/OpenMesh/Core/IO/writer/PLYWriter.hh b/src/OpenMesh/Core/IO/writer/PLYWriter.hh
index d05978c7..5e7cfb92 100644
--- a/src/OpenMesh/Core/IO/writer/PLYWriter.hh
+++ b/src/OpenMesh/Core/IO/writer/PLYWriter.hh
@@ -102,7 +102,7 @@ public:
 
   bool write(std::ostream&, BaseExporter&, const Options& _writeOptions, std::streamsize _precision = 6) const override;
 
-  size_t binary_size(BaseExporter& _be, Options _opt) const override;
+  size_t binary_size(BaseExporter& _be, const Options& _opt) const override;
 
   enum ValueType {
     Unsupported = 0,
diff --git a/src/OpenMesh/Core/IO/writer/STLWriter.cc b/src/OpenMesh/Core/IO/writer/STLWriter.cc
index 428a085f..c01e1353 100644
--- a/src/OpenMesh/Core/IO/writer/STLWriter.cc
+++ b/src/OpenMesh/Core/IO/writer/STLWriter.cc
@@ -409,7 +409,7 @@ write_stlb(std::ostream& _out, BaseExporter& _be, Options /* _opt */, std::strea
 
 size_t
 _STLWriter_::
-binary_size(BaseExporter& _be, Options /* _opt */) const
+binary_size(BaseExporter& _be, const Options& /* _opt */) const
 {
   size_t bytes(0);
   size_t _12floats(12*sizeof(float));
diff --git a/src/OpenMesh/Core/IO/writer/STLWriter.hh b/src/OpenMesh/Core/IO/writer/STLWriter.hh
index 13e12925..4244df14 100644
--- a/src/OpenMesh/Core/IO/writer/STLWriter.hh
+++ b/src/OpenMesh/Core/IO/writer/STLWriter.hh
@@ -95,7 +95,7 @@ public:
 
   bool write(std::ostream&, BaseExporter&, const Options& _writeOptions, std::streamsize _precision = 6) const override;
 
-  size_t binary_size(BaseExporter&, Options) const override;
+  size_t binary_size(BaseExporter&, const Options&) const override;
 
 private:
   bool write_stla(const std::string&, BaseExporter&, Options) const;
diff --git a/src/OpenMesh/Core/IO/writer/VTKWriter.hh b/src/OpenMesh/Core/IO/writer/VTKWriter.hh
index 50a5d1c4..8887a40e 100644
--- a/src/OpenMesh/Core/IO/writer/VTKWriter.hh
+++ b/src/OpenMesh/Core/IO/writer/VTKWriter.hh
@@ -35,7 +35,7 @@ public:
     bool write(const std::string&, BaseExporter&, const Options& _writeOptions, std::streamsize _precision = 6) const override;
     bool write(std::ostream&, BaseExporter&, const Options& _writeOptions, std::streamsize _precision = 6) const override;
 
-    size_t binary_size(BaseExporter&, Options) const override { return 0; }
+    size_t binary_size(BaseExporter&, const Options&) const override { return 0; }
 };
 
 //== TYPE DEFINITION ==========================================================