diff --git a/libp2p/pubsub/floodsub.py b/libp2p/pubsub/floodsub.py
index bac0bd7..678e509 100644
--- a/libp2p/pubsub/floodsub.py
+++ b/libp2p/pubsub/floodsub.py
@@ -77,10 +77,12 @@ class FloodSub(IPubsubRouter):
         :param pubsub_msg: pubsub message in protobuf.
         """
 
-        peers_gen = self._get_peers_to_send(
-            pubsub_msg.topicIDs,
-            msg_forwarder=msg_forwarder,
-            origin=ID(pubsub_msg.from_id),
+        peers_gen = set(
+            self._get_peers_to_send(
+                pubsub_msg.topicIDs,
+                msg_forwarder=msg_forwarder,
+                origin=ID(pubsub_msg.from_id),
+            )
         )
         rpc_msg = rpc_pb2.RPC(publish=[pubsub_msg])
 
diff --git a/libp2p/pubsub/gossipsub.py b/libp2p/pubsub/gossipsub.py
index 045ef39..1969d4f 100644
--- a/libp2p/pubsub/gossipsub.py
+++ b/libp2p/pubsub/gossipsub.py
@@ -148,11 +148,9 @@ class GossipSub(IPubsubRouter):
 
         for topic in self.mesh:
             if peer_id in self.mesh[topic]:
-                # Delete the entry if no other peers left
                 self.mesh[topic].remove(peer_id)
         for topic in self.fanout:
             if peer_id in self.fanout[topic]:
-                # Delete the entry if no other peers left
                 self.fanout[topic].remove(peer_id)
 
         self.peers_to_protocol.pop(peer_id, None)
diff --git a/libp2p/pubsub/pubsub.py b/libp2p/pubsub/pubsub.py
index a44aa05..6e9d948 100644
--- a/libp2p/pubsub/pubsub.py
+++ b/libp2p/pubsub/pubsub.py
@@ -289,24 +289,22 @@ class Pubsub:
             logger.debug("fail to add new peer %s, error %s", peer_id, error)
             return
 
-        self.peers[peer_id] = stream
-
         # Send hello packet
         hello = self.get_hello_packet()
         try:
             await stream.write(encode_varint_prefixed(hello.SerializeToString()))
         except StreamClosed:
             logger.debug("Fail to add new peer %s: stream closed", peer_id)
-            del self.peers[peer_id]
             return
         # TODO: Check if the peer in black list.
         try:
             self.router.add_peer(peer_id, stream.get_protocol())
         except Exception as error:
             logger.debug("fail to add new peer %s, error %s", peer_id, error)
-            del self.peers[peer_id]
             return
 
+        self.peers[peer_id] = stream
+
         logger.debug("added new peer %s", peer_id)
 
     def _handle_dead_peer(self, peer_id: ID) -> None:
@@ -316,7 +314,6 @@ class Pubsub:
 
         for topic in self.peer_topics:
             if peer_id in self.peer_topics[topic]:
-                # Delete the entry if no other peers left
                 self.peer_topics[topic].remove(peer_id)
 
         self.router.remove_peer(peer_id)
@@ -360,7 +357,6 @@ class Pubsub:
         else:
             if sub_message.topicid in self.peer_topics:
                 if origin_id in self.peer_topics[sub_message.topicid]:
-                    # Delete the entry if no other peers left
                     self.peer_topics[sub_message.topicid].remove(origin_id)
 
     # FIXME(mhchia): Change the function name?