diff -r a2d5fd4c309a -r 921d5bf41ac2 lemon/hartmann_orlin.h
--- a/lemon/hartmann_orlin.h	Wed Nov 18 14:38:38 2009 +0100
+++ b/lemon/hartmann_orlin.h	Wed Nov 18 21:21:26 2009 +0100
@@ -598,7 +598,9 @@
             }
           }
           level[u] = Pair(i, j);
-          u = _gr.source(_data[u][j].pred);
+          if (j != 0) {
+	    u = _gr.source(_data[u][j].pred);
+	  }
         }
       }