diff --git a/mininet/topo.py b/mininet/topo.py
index bc60c05..8b7e463 100644
--- a/mininet/topo.py
+++ b/mininet/topo.py
@@ -156,8 +156,7 @@ class Topo( object ):
         port1, port2 = self.addPort( node1, node2, port1, port2 )
         opts = dict( opts )
         opts.update( node1=node1, node2=node2, port1=port1, port2=port2 )
-        self.g.add_edge(node1, node2, key, opts )
-        return key
+        return self.g.add_edge(node1, node2, key, opts )
 
     def nodes( self, sort=True ):
         "Return nodes in graph"