diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index 9f5c98694..7ca8d49c5 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -331,7 +331,6 @@ class FederationServer(FederationBase):
         )
         if already_seen:
             logger.debug("Already seen pdu %s", pdu.event_id)
-            defer.returnValue({})
             return
 
         # Check signature.
@@ -418,7 +417,7 @@ class FederationServer(FederationBase):
             except:
                 logger.warn("Failed to get state for event: %s", pdu.event_id)
 
-        ret = yield self.handler.on_receive_pdu(
+        yield self.handler.on_receive_pdu(
             origin,
             pdu,
             backfilled=False,
@@ -426,8 +425,6 @@ class FederationServer(FederationBase):
             auth_chain=auth_chain,
         )
 
-        defer.returnValue(ret)
-
     def __str__(self):
         return "<ReplicationLayer(%s)>" % self.server_name