diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index 51e3fdea0..e791a1266 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -143,30 +143,6 @@ class FederationServer(FederationBase):
         results = []
 
         for pdu in pdu_list:
-            # check that it's actually being sent from a valid destination to
-            # workaround bug #1753 in 0.18.5 and 0.18.6
-            if transaction.origin != get_domain_from_id(pdu.event_id):
-                # We continue to accept join events from any server; this is
-                # necessary for the federation join dance to work correctly.
-                # (When we join over federation, the "helper" server is
-                # responsible for sending out the join event, rather than the
-                # origin. See bug #1893).
-                if not (
-                    pdu.type == 'm.room.member' and
-                    pdu.content and
-                    pdu.content.get("membership", None) == 'join'
-                ):
-                    logger.info(
-                        "Discarding PDU %s from invalid origin %s",
-                        pdu.event_id, transaction.origin
-                    )
-                    continue
-                else:
-                    logger.info(
-                        "Accepting join PDU %s from %s",
-                        pdu.event_id, transaction.origin
-                    )
-
             try:
                 yield self._handle_received_pdu(transaction.origin, pdu)
                 results.append({})
@@ -520,6 +496,30 @@ class FederationServer(FederationBase):
         Returns (Deferred): completes with None
         Raises: FederationError if the signatures / hash do not match
     """
+        # check that it's actually being sent from a valid destination to
+        # workaround bug #1753 in 0.18.5 and 0.18.6
+        if origin != get_domain_from_id(pdu.event_id):
+            # We continue to accept join events from any server; this is
+            # necessary for the federation join dance to work correctly.
+            # (When we join over federation, the "helper" server is
+            # responsible for sending out the join event, rather than the
+            # origin. See bug #1893).
+            if not (
+                pdu.type == 'm.room.member' and
+                pdu.content and
+                pdu.content.get("membership", None) == 'join'
+            ):
+                logger.info(
+                    "Discarding PDU %s from invalid origin %s",
+                    pdu.event_id, origin
+                )
+                return
+            else:
+                logger.info(
+                    "Accepting join PDU %s from %s",
+                    pdu.event_id, origin
+                )
+
         # Check signature.
         try:
             pdu = yield self._check_sigs_and_hash(pdu)