diff --git a/dune/vtk/gridcreators/serialgridcreator.hh b/dune/vtk/gridcreators/serialgridcreator.hh
index 75aeb13b76b5ccac3bc5ac94f36d39009e281c40..d729149529ef8c64a7c6a30adf2dc0973ed243d2 100644
--- a/dune/vtk/gridcreators/serialgridcreator.hh
+++ b/dune/vtk/gridcreators/serialgridcreator.hh
@@ -11,6 +11,7 @@
 
 namespace Dune
 {
+  // create a distributed grid on rank 0. Needs to be load balanced afterwards.
   template <class Grid>
   struct SerialGridCreator
       : public GridCreatorInterface<Grid, SerialGridCreator<Grid>>
diff --git a/dune/vtk/vtkwriterinterface.impl.hh b/dune/vtk/vtkwriterinterface.impl.hh
index ab08febbefc40218e6e76ec18bb24ca1de041786..0a4a9bfe14814a99eeb386ea038ffc51e4d169d8 100644
--- a/dune/vtk/vtkwriterinterface.impl.hh
+++ b/dune/vtk/vtkwriterinterface.impl.hh
@@ -162,10 +162,10 @@ void VtkWriterInterface<GV,DC>
 namespace Impl {
 
   template <class T, std::enable_if_t<(sizeof(T)>1), int> = 0>
-  T const& printable (T const& t) { return t; }
+  inline T const& printable (T const& t) { return t; }
 
-  std::int16_t printable (std::int8_t c) { return std::int16_t(c); }
-  std::uint16_t printable (std::uint8_t c) { return std::uint16_t(c); }
+  inline std::int16_t printable (std::int8_t c) { return std::int16_t(c); }
+  inline std::uint16_t printable (std::uint8_t c) { return std::uint16_t(c); }
 
 } // end namespace Impl