diff --git a/istl/paamg/dependency.hh b/istl/paamg/dependency.hh
index 9789e72d8c6cbe362d49223a7d3a741a41fc9c9e..54ce91c5c45e8114560078c4fa847303124bb1d2 100644
--- a/istl/paamg/dependency.hh
+++ b/istl/paamg/dependency.hh
@@ -24,8 +24,6 @@ namespace Dune
      * @brief Provides classes for initializing the link attributes of a matrix graph.
      */
 
-    class EdgeProperties;
-
     /**
      * @brief Class representing the properties of an ede in the matrix graph.
      *
@@ -102,12 +100,15 @@ namespace Dune
        */
       void printFlags() const;
     };
+
     /**
      * @brief Class representing a node in the matrix graph.
      *
      * Contains methods for getting and setting node attributes.
      */
     class VertexProperties {
+      friend std::ostream& operator<<(std::ostream& os, const VertexProperties& props);
+
     private:
       enum { ISOLATED, VISITED, FRONT, EXCLUDED, SIZE };
 
@@ -247,6 +248,11 @@ namespace Dune
     }
 
 
+    inline std::ostream& operator<<(std::ostream& os, const VertexProperties& props)
+    {
+      return os << props.flags_;
+    }
+
     inline VertexProperties::VertexProperties()
       : flags_(0)
     {}