diff --git a/src/graph/edge.cc b/src/graph/edge.cc
index 53d3b3d52b7a9d40918102e531e87f03e944497a..61373e3a6d893719944e3c3132005b81f6ebd045 100644
--- a/src/graph/edge.cc
+++ b/src/graph/edge.cc
@@ -340,6 +340,7 @@ namespace hpp {
 	    hppDout(info, "q2 = " << displayConfig (q2)
                     << " does not satisfy the constraints of edge "
                     << name ());
+	    hppDout (info, "q1 = " << displayConfig (q1));
 	    return false;
 	  }
         } else {