diff --git a/libp2p/pubsub/pubsub.py b/libp2p/pubsub/pubsub.py
index 9a70b40b..aaf08ccd 100644
--- a/libp2p/pubsub/pubsub.py
+++ b/libp2p/pubsub/pubsub.py
@@ -1,6 +1,7 @@
 import asyncio
+from collections import namedtuple
 import time
-from typing import TYPE_CHECKING, Any, Dict, List, Tuple
+from typing import Any, Awaitable, Callable, Dict, List, Tuple, Union, TYPE_CHECKING
 
 from lru import LRU
 
@@ -20,6 +21,9 @@ def get_msg_id(msg: rpc_pb2.Message) -> Tuple[bytes, bytes]:
     return (msg.seqno, msg.from_id)
 
 
+TopicValidator = namedtuple("TopicValidator", ["validator", "is_async"])
+
+
 class Pubsub:
 
     host: IHost
@@ -41,6 +45,8 @@ class Pubsub:
     peer_topics: Dict[str, List[ID]]
     peers: Dict[ID, INetStream]
 
+    topic_validators: Dict[str, TopicValidator]
+
     # NOTE: Be sure it is increased atomically everytime.
     counter: int  # uint64
 
@@ -93,6 +99,9 @@ class Pubsub:
         # Create peers map, which maps peer_id (as string) to stream (to a given peer)
         self.peers = {}
 
+        # Map of topic to topic validator
+        self.topic_validators = {}
+
         self.counter = time.time_ns()
 
         # Call handle peer to keep waiting for updates to peer queue