diff -uNr a/blatta/lib/state.py b/blatta/lib/state.py
--- a/blatta/lib/state.py 302f32cc4525b593ed2b8e61ae3610003f5811f59778e1085b3e6cb28dd87646d77758a48b7bb7643d41d7602524b2cb35f2d7c9d96fc1d3e4f5136cd5a1a6f8
+++ b/blatta/lib/state.py 3a207e51557942e77a01545c65b138ae91f4528ab5fac9d925778c6e5ab3a07421d982a1623255a7213e135cdbe162d7ffa4a1961fb68b412d8e242269054151
@@ -352,6 +352,6 @@

     def is_duplicate(self, peers, peer):
         for existing_peer in peers:
-            if existing_peer.address == peer.address and existing_peer.port == peer.port:
+            if not existing_peer.address is None and existing_peer.address == peer.address and existing_peer.port == peer.port:
                return True
         return False