diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py

index 0f9c82fd06..77c81fe2da 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -23,6 +23,7 @@ from synapse.api.errors import (
 from synapse.api.constants import EventTypes, Membership, RejectedReason
 from synapse.util.logutils import log_function
 from synapse.util.async import run_on_reactor
+from synapse.util.frozenutils import unfreeze
 from synapse.crypto.event_signing import (
     compute_event_signature, add_hashes_and_signatures,
 )
@@ -311,7 +312,7 @@ class FederationHandler(BaseHandler):
         self.room_queues[room_id] = []
 
         builder = self.event_builder_factory.new(
-            event.get_pdu_json()
+            unfreeze(event.get_pdu_json())
         )
 
         handled_events = set()
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py

index 0369b907a5..914742d913 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -462,7 +462,7 @@ class RoomMemberHandler(BaseHandler):
                 room_hosts,
                 room_id,
                 event.user_id,
-                event.get_dict()["content"],  # FIXME To get a non-frozen dict
+                event.content,  # FIXME To get a non-frozen dict
                 context
             )
         else: