diff --git a/src/unitvector.hh b/src/unitvector.hh
index e583af79c8641846550ce7726d277086ef4a23f4..1fc9e8f944522e3851fd1aef8071b5ca6e04f071 100644
--- a/src/unitvector.hh
+++ b/src/unitvector.hh
@@ -8,6 +8,9 @@ class UnitVector
 {
 public:
 
+    /** \brief The type used for coordinates */
+    typedef double ctype;
+
     typedef Dune::FieldVector<double,dim> TangentVector;
     typedef Dune::FieldVector<double,dim> EmbeddedTangentVector;