diff --git a/src/vtk.hh b/src/vtk.hh
index e1e19c05e4cd7bc27825b3a65f1c51379043ade8..a5b62db35604bfc91db7b9e0ba333a3ed2430bb0 100644
--- a/src/vtk.hh
+++ b/src/vtk.hh
@@ -1,6 +1,8 @@
 #ifndef VTK_HH
 #define VTK_HH
 
+#include <string>
+
 template <class VertexBasis, class CellBasis> class MyVTKWriter {
   CellBasis const &cellBasis;
   VertexBasis const &vertexBasis;