diff --git a/synapse/http/endpoint.py b/synapse/http/endpoint.py
index 928c1c740..80da87058 100644
--- a/synapse/http/endpoint.py
+++ b/synapse/http/endpoint.py
@@ -74,7 +74,7 @@ def matrix_federation_endpoint(reactor, destination, ssl_context_factory=None,
             reactor, "matrix", domain, protocol="tcp",
             default_port=default_port, endpoint=transport_endpoint,
             endpoint_kw_args=endpoint_kw_args
-        ))
+        ), reactor)
     else:
         return _WrappingEndpointFac(transport_endpoint(
             reactor, domain, port, **endpoint_kw_args