diff --git a/opm/core/utility/writeVtkData.hpp b/opm/core/utility/writeVtkData.hpp
index 200b2b261..96cdfac22 100644
--- a/opm/core/utility/writeVtkData.hpp
+++ b/opm/core/utility/writeVtkData.hpp
@@ -26,25 +26,23 @@
 #include <vector>
 #include <tr1/array>
 #include <iosfwd>
+#include <opm/core/utility/DataMap.hpp>
 
 struct UnstructuredGrid;
 
 namespace Opm
 {
 
-    /// Intended to map strings (giving the output field names) to data.
-    typedef std::map<std::string, const std::vector<double>*> DataMap;
-
     /// Vtk output for cartesian grids.
     void writeVtkData(const std::tr1::array<int, 3>& dims,
-		      const std::tr1::array<double, 3>& cell_size,
-		      const DataMap& data,
-		      std::ostream& os);
+                      const std::tr1::array<double, 3>& cell_size,
+                      const DataMap& data,
+                      std::ostream& os);
 
     /// Vtk output for general grids.
     void writeVtkData(const UnstructuredGrid& grid,
-		      const DataMap& data,
-		      std::ostream& os);
+                      const DataMap& data,
+                      std::ostream& os);
 } // namespace Opm
 
 #endif // OPM_WRITEVTKDATA_HEADER_INCLUDED