diff --git a/model.py b/model.py
index 9af433d..62c02d3 100644
--- a/model.py
+++ b/model.py
@@ -1498,7 +1498,7 @@ def undo(self, change_no):
 
          self.graph.add_node(router)
          for (u, v, w) in edges:
-            self.graph.add_edge(u, v, weight=w)
+            self.graph.add_edge(u, v, w)
 
       del self.changes[idx]