diff --git a/synapse/http/client.py b/synapse/http/client.py
index c9479c81ff6b..d64713a10ac6 100644
--- a/synapse/http/client.py
+++ b/synapse/http/client.py
@@ -844,6 +844,7 @@ def __init__(
 
         self.agent: IAgent = ReplicationAgent(
             hs.get_reactor(),
+            hs.config.worker.instance_map,
             contextFactory=hs.get_http_client_context_factory(),
             pool=pool,
         )
diff --git a/synapse/http/replicationagent.py b/synapse/http/replicationagent.py
index 5ecd08be0f52..8cd7a16cf482 100644
--- a/synapse/http/replicationagent.py
+++ b/synapse/http/replicationagent.py
@@ -13,7 +13,7 @@
 # limitations under the License.
 
 import logging
-from typing import Optional
+from typing import Any, Dict, Optional
 
 from zope.interface import implementer
 
@@ -44,9 +44,11 @@ class ReplicationEndpointFactory:
     def __init__(
         self,
         reactor: ISynapseReactor,
+        instance_map: Dict[str, Any],
         context_factory: IPolicyForHTTPS,
     ) -> None:
         self.reactor = reactor
+        self.instance_map = instance_map
         self.context_factory = context_factory
 
     def endpointForURI(self, uri: URI) -> IStreamClientEndpoint:
@@ -80,6 +82,7 @@ class ReplicationAgent(_AgentBase):
     def __init__(
         self,
         reactor: ISynapseReactor,
+        instance_map: Dict[str, Any],
         contextFactory: IPolicyForHTTPS,
         connectTimeout: Optional[float] = None,
         bindAddress: Optional[bytes] = None,
@@ -102,7 +105,8 @@ def __init__(
                 created.
         """
         _AgentBase.__init__(self, reactor, pool)
-        endpoint_factory = ReplicationEndpointFactory(reactor, contextFactory)
+        endpoint_factory = ReplicationEndpointFactory(
+            reactor, instance_map, contextFactory
         self._endpointFactory = endpoint_factory
 
     def request(