diff --git a/synapse/crypto/event_signing.py b/synapse/crypto/event_signing.py
index 209f9d73f..b189f0bb2 100644
--- a/synapse/crypto/event_signing.py
+++ b/synapse/crypto/event_signing.py
@@ -15,7 +15,7 @@
 # limitations under the License.
 
 
-from synapse.api.events.utils import prune_event
+from synapse.events.utils import prune_event
 from syutil.jsonutil import encode_canonical_json
 from syutil.base64util import encode_base64, decode_base64
 from syutil.crypto.jsonsign import sign_json
diff --git a/synapse/events/__init__.py b/synapse/events/__init__.py
index 6a05ba2d1..58edf2bc8 100644
--- a/synapse/events/__init__.py
+++ b/synapse/events/__init__.py
@@ -85,10 +85,10 @@ class EventBase(object):
         return hasattr(self, "state_key")
 
     def get_dict(self):
-        d = dict(self._original)
+        d = dict(self._event_dict)
         d.update({
-            "signatures": self._signatures,
-            "unsigned": self._unsigned,
+            "signatures": self.signatures,
+            "unsigned": self.unsigned,
         })
 
         return d
@@ -128,7 +128,7 @@ class FrozenEvent(EventBase):
     @staticmethod
     def from_event(event):
         e = FrozenEvent(
-            event.event_dict()
+            event.get_pdu_json()
         )
 
         e.internal_metadata = event.internal_metadata
diff --git a/synapse/events/builder.py b/synapse/events/builder.py
index 39b4d2a2a..0b8caf931 100644
--- a/synapse/events/builder.py
+++ b/synapse/events/builder.py
@@ -22,10 +22,13 @@ from synapse.util.stringutils import random_string
 
 class EventBuilder(EventBase):
     def __init__(self, key_values={}):
-        super(FrozenEvent, self).__init__(
+        super(EventBuilder, self).__init__(
             key_values,
         )
 
+    def update_event_key(self, key, value):
+        self._event_dict[key] = value
+
     def update_event_keys(self, other_dict):
         self._event_dict.update(other_dict)
 
diff --git a/synapse/federation/replication.py b/synapse/federation/replication.py
index bd56a4c10..b11df9e5c 100644
--- a/synapse/federation/replication.py
+++ b/synapse/federation/replication.py
@@ -74,6 +74,7 @@ class ReplicationLayer(object):
         self._clock = hs.get_clock()
 
         self.event_factory = hs.get_event_factory()
+        self.event_builder_factory = hs.get_event_builder_factory()
 
     def set_handler(self, handler):
         """Sets the handler that the replication layer will use to communicate
@@ -658,19 +659,14 @@ class ReplicationLayer(object):
         return "<ReplicationLayer(%s)>" % self.server_name
 
     def event_from_pdu_json(self, pdu_json, outlier=False):
-        #TODO: Check we have all the PDU keys here
-        pdu_json.setdefault("hashes", {})
-        pdu_json.setdefault("signatures", {})
-        sender = pdu_json.pop("sender", None)
-        if sender is not None:
-            pdu_json["user_id"] = sender
-        state_hash = pdu_json.get("unsigned", {}).pop("state_hash", None)
-        if state_hash is not None:
-            pdu_json["state_hash"] = state_hash
-        return self.event_factory.create_event(
-            pdu_json["type"], outlier=outlier, **pdu_json
+        builder = self.event_builder_factory.new(
+            pdu_json
         )
 
+        builder.internal_metadata = outlier
+
+        return builder.build()
+
 
 class _TransactionQueue(object):
     """This class makes sure we only have one transaction in flight at
diff --git a/synapse/handlers/_base.py b/synapse/handlers/_base.py
index 890b51be3..4052d0e1e 100644
--- a/synapse/handlers/_base.py
+++ b/synapse/handlers/_base.py
@@ -46,6 +46,8 @@ class BaseHandler(object):
         self.signing_key = hs.config.signing_key[0]
         self.server_name = hs.hostname
 
+        self.event_builder_factory = hs.get_event_builder_factory()
+
     def ratelimit(self, user_id):
         time_now = self.clock.time()
         allowed, time_allowed = self.ratelimiter.send_message(
@@ -92,7 +94,7 @@ class BaseHandler(object):
         builder.prev_events = prev_events
         builder.depth = depth
 
-        auth_events = yield self.auth.get_event_auth(builder, curr_state)
+        auth_events = yield self.auth.get_auth_events(builder, curr_state)
 
         builder.update_event_key("auth_events", auth_events)
 
@@ -105,7 +107,7 @@ class BaseHandler(object):
         auth_ids = zip(*auth_events)[0]
         curr_auth_events = {
             k: v
-            for k, v in curr_state
+            for k, v in curr_state.items()
             if v.event_id in auth_ids
         }
 
@@ -119,14 +121,16 @@ class BaseHandler(object):
         )
 
     @defer.inlineCallbacks
-    def _handle_new_client_event(self, event, context):
+    def handle_new_client_event(self, event, context, extra_destinations=[],
+                                extra_users=[], suppress_auth=False):
         # We now need to go and hit out to wherever we need to hit out to.
 
-        self.auth.check(event, auth_events=context.auth_events)
+        if not suppress_auth:
+            self.auth.check(event, auth_events=context.auth_events)
 
         yield self.store.persist_event(event)
 
-        destinations = set()
+        destinations = set(extra_destinations)
         for k, s in context.current_state.items():
             try:
                 if k[0] == EventTypes.Member:
@@ -139,7 +143,7 @@ class BaseHandler(object):
                     "Failed to get destination from event %s", s.event_id
                 )
 
-        yield self.notifier.on_new_room_event(event)
+        yield self.notifier.on_new_room_event(event, extra_users=extra_users)
 
         federation_handler = self.hs.get_handlers().federation_handler
         yield federation_handler.handle_new_event(
diff --git a/synapse/handlers/directory.py b/synapse/handlers/directory.py
index b95c4b8bf..76fb897f2 100644
--- a/synapse/handlers/directory.py
+++ b/synapse/handlers/directory.py
@@ -148,16 +148,12 @@ class DirectoryHandler(BaseHandler):
     def send_room_alias_update_event(self, user_id, room_id):
         aliases = yield self.store.get_aliases_for_room(room_id)
 
-        event = self.event_factory.create_event(
-            etype=RoomAliasesEvent.TYPE,
-            state_key=self.hs.hostname,
-            room_id=room_id,
-            user_id=user_id,
-            content={"aliases": aliases},
-        )
+        msg_handler = self.hs.get_handlers().message_handler
+        yield msg_handler.handle_event({
+            "type": RoomAliasesEvent.TYPE,
+            "state_key": self.hs.hostname,
+            "room_id": room_id,
+            "sender": user_id,
+            "content": {"aliases": aliases},
+        })
 
-        snapshot = yield self.store.snapshot_room(event)
-
-        yield self._on_new_room_event(
-            event, snapshot, extra_users=[user_id], suppress_auth=True
-        )
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index 7bd36e415..b4a28ea3c 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -421,16 +421,17 @@ class FederationHandler(BaseHandler):
         join event for the room and return that. We don *not* persist or
         process it until the other server has signed it and sent it back.
         """
-        event = self.event_factory.create_event(
-            etype=RoomMemberEvent.TYPE,
-            content={"membership": Membership.JOIN},
-            room_id=context,
-            user_id=user_id,
-            state_key=user_id,
-        )
+        builder = self.event_builder_factory.new({
+            "type": RoomMemberEvent.TYPE,
+            "content": {"membership": Membership.JOIN},
+            "room_id": context,
+            "sender": user_id,
+            "state_key": user_id,
+        })
 
-        snapshot = yield self.store.snapshot_room(event)
-        snapshot.fill_out_prev_events(event)
+        event, context = yield self._create_new_client_event(
+            builder=builder,
+        )
 
         yield self.state_handler.annotate_event_with_state(event)
         yield self.auth.add_auth_events(event)
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 269d6622e..485d8e817 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -15,7 +15,7 @@
 
 from twisted.internet import defer
 
-from synapse.api.constants import Membership
+from synapse.api.constants import EventTypes, Membership
 from synapse.api.errors import RoomError
 from synapse.streams.config import PaginationConfig
 from synapse.util.logcontext import PreserveLoggingContext
@@ -133,6 +133,27 @@ class MessageHandler(BaseHandler):
 
         defer.returnValue(chunk)
 
+    @defer.inlineCallbacks
+    def handle_event(self, event_dict):
+        builder = self.event_builder_factory.new(event_dict)
+
+        event, context = yield self._create_new_client_event(
+            builder=builder,
+        )
+
+        # TODO: self.validator.validate(event)
+
+        if event.type == EventTypes.Member:
+            member_handler = self.hs.get_handlers().room_member_handler
+            yield member_handler.change_membership(event, context)
+        else:
+            yield self.handle_new_client_event(
+                event=event,
+                context=context,
+            )
+
+        defer.returnValue(event)
+
     @defer.inlineCallbacks
     def store_room_data(self, event=None):
         """ Stores data for a room.
diff --git a/synapse/handlers/profile.py b/synapse/handlers/profile.py
index 0116ba535..f2abbc5df 100644
--- a/synapse/handlers/profile.py
+++ b/synapse/handlers/profile.py
@@ -210,14 +210,11 @@ class ProfileHandler(BaseHandler):
                 "collect_presencelike_data", user, content
             )
 
-            new_event = self.event_factory.create_event(
-                etype=j.type,
-                room_id=j.room_id,
-                state_key=j.state_key,
-                content=content,
-                user_id=j.state_key,
-            )
-
-            yield self._on_new_room_event(
-                new_event, snapshot, suppress_auth=True
-            )
+            msg_handler = self.hs.get_handlers().message_handler
+            yield msg_handler.handle_event({
+                "type": j.type,
+                "room_id": j.room_id,
+                "state_key": j.state_key,
+                "content": content,
+                "sender": j.state_key,
+            })
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index 52a978882..f0ffd62b7 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -123,59 +123,37 @@ class RoomCreationHandler(BaseHandler):
             user, room_id, is_public=is_public
         )
 
-        room_member_handler = self.hs.get_handlers().room_member_handler
-
-        @defer.inlineCallbacks
-        def handle_event(event):
-            snapshot = yield self.store.snapshot_room(event)
-
-            logger.debug("Event: %s", event)
-
-            if event.type == RoomMemberEvent.TYPE:
-                yield room_member_handler.change_membership(
-                    event,
-                    do_auth=True
-                )
-            else:
-                yield self._on_new_room_event(
-                    event, snapshot, extra_users=[user], suppress_auth=True
-                )
+        msg_handler = self.hs.get_handlers().message_handler
 
         for event in creation_events:
-            yield handle_event(event)
+            yield msg_handler.handle_event(event)
 
         if "name" in config:
             name = config["name"]
-            name_event = self.event_factory.create_event(
-                etype=RoomNameEvent.TYPE,
-                room_id=room_id,
-                user_id=user_id,
-                content={"name": name},
-            )
-
-            yield handle_event(name_event)
+            yield msg_handler.handle_event({
+                "type": RoomNameEvent.TYPE,
+                "room_id": room_id,
+                "sender": user_id,
+                "content": {"name": name},
+            })
 
         if "topic" in config:
             topic = config["topic"]
-            topic_event = self.event_factory.create_event(
-                etype=RoomTopicEvent.TYPE,
-                room_id=room_id,
-                user_id=user_id,
-                content={"topic": topic},
-            )
+            yield msg_handler.handle_event({
+                "type": RoomTopicEvent.TYPE,
+                "room_id": room_id,
+                "sender": user_id,
+                "content": {"topic": topic},
+            })
 
-            yield handle_event(topic_event)
-
-        content = {"membership": Membership.INVITE}
         for invitee in invite_list:
-            invite_event = self.event_factory.create_event(
-                etype=RoomMemberEvent.TYPE,
-                state_key=invitee,
-                room_id=room_id,
-                user_id=user_id,
-                content=content
-            )
-            yield handle_event(invite_event)
+            yield msg_handler.handle_event({
+                "type": RoomMemberEvent.TYPE,
+                "state_key": invitee,
+                "room_id": room_id,
+                "user_id": user_id,
+                "content": {"membership": Membership.INVITE},
+            })
 
         result = {"room_id": room_id}
 
@@ -192,22 +170,25 @@ class RoomCreationHandler(BaseHandler):
 
         event_keys = {
             "room_id": room_id,
-            "user_id": creator_id,
+            "sender": creator_id,
         }
 
-        def create(etype, **content):
-            return self.event_factory.create_event(
-                etype=etype,
-                content=content,
-                **event_keys
-            )
+        def create(etype, content):
+            e = {
+                "type": etype,
+                "content": content,
+            }
+
+            e.update(event_keys)
+
+            return e
 
         creation_event = create(
             etype=RoomCreateEvent.TYPE,
-            creator=creator.to_string(),
+            content={"creator": creator.to_string()},
         )
 
-        join_event = self.event_factory.create_event(
+        join_event = create(
             etype=RoomMemberEvent.TYPE,
             state_key=creator_id,
             content={
@@ -216,7 +197,7 @@ class RoomCreationHandler(BaseHandler):
             **event_keys
         )
 
-        power_levels_event = self.event_factory.create_event(
+        power_levels_event = create(
             etype=RoomPowerLevelsEvent.TYPE,
             content={
                 "users": {
@@ -233,13 +214,12 @@ class RoomCreationHandler(BaseHandler):
                 "kick": 50,
                 "redact": 50
             },
-            **event_keys
         )
 
         join_rule = JoinRules.PUBLIC if is_public else JoinRules.INVITE
         join_rules_event = create(
             etype=RoomJoinRulesEvent.TYPE,
-            join_rule=join_rule,
+            content={"join_rule": join_rule},
         )
 
         return [
@@ -351,7 +331,7 @@ class RoomMemberHandler(BaseHandler):
         defer.returnValue(member)
 
     @defer.inlineCallbacks
-    def change_membership(self, event=None, do_auth=True):
+    def change_membership(self, event, context, do_auth=True):
         """ Change the membership status of a user in a room.
 
         Args:
@@ -361,8 +341,6 @@ class RoomMemberHandler(BaseHandler):
         """
         target_user_id = event.state_key
 
-        snapshot = yield self.store.snapshot_room(event)
-
         ## TODO(markjh): get prev state from snapshot.
         prev_state = yield self.store.get_room_member(
             target_user_id, event.room_id
@@ -374,7 +352,7 @@ class RoomMemberHandler(BaseHandler):
         # if this HS is not currently in the room, i.e. we have to do the
         # invite/join dance.
         if event.membership == Membership.JOIN:
-            yield self._do_join(event, snapshot, do_auth=do_auth)
+            yield self._do_join(event, context, do_auth=do_auth)
         else:
             # This is not a JOIN, so we can handle it normally.
 
@@ -387,7 +365,7 @@ class RoomMemberHandler(BaseHandler):
             yield self._do_local_membership_update(
                 event,
                 membership=event.content["membership"],
-                snapshot=snapshot,
+                context=context,
                 do_auth=do_auth,
             )
 
@@ -409,23 +387,21 @@ class RoomMemberHandler(BaseHandler):
         host = hosts[0]
 
         content.update({"membership": Membership.JOIN})
-        new_event = self.event_factory.create_event(
-            etype=RoomMemberEvent.TYPE,
-            state_key=joinee.to_string(),
-            room_id=room_id,
-            user_id=joinee.to_string(),
-            membership=Membership.JOIN,
-            content=content,
-        )
+        event, context = yield self.create_new_client_event({
+            "type": RoomMemberEvent.TYPE,
+            "state_key": joinee.to_string(),
+            "room_id": room_id,
+            "sender": joinee.to_string(),
+            "membership": Membership.JOIN,
+            "content": content,
+        })
 
-        snapshot = yield self.store.snapshot_room(new_event)
-
-        yield self._do_join(new_event, snapshot, room_host=host, do_auth=True)
+        yield self._do_join(event, context, room_host=host, do_auth=True)
 
         defer.returnValue({"room_id": room_id})
 
     @defer.inlineCallbacks
-    def _do_join(self, event, snapshot, room_host=None, do_auth=True):
+    def _do_join(self, event, context, room_host=None, do_auth=True):
         joinee = self.hs.parse_userid(event.state_key)
         # room_id = RoomID.from_string(event.room_id, self.hs)
         room_id = event.room_id
@@ -470,7 +446,7 @@ class RoomMemberHandler(BaseHandler):
         if should_do_dance:
             handler = self.hs.get_handlers().federation_handler
             have_joined = yield handler.do_invite_join(
-                room_host, room_id, event.user_id, event.content, snapshot
+                room_host, room_id, event.user_id, event.content, context
             )
 
         # We want to do the _do_update inside the room lock.
@@ -480,7 +456,7 @@ class RoomMemberHandler(BaseHandler):
             yield self._do_local_membership_update(
                 event,
                 membership=event.content["membership"],
-                snapshot=snapshot,
+                context=context,
                 do_auth=do_auth,
             )
 
@@ -530,7 +506,7 @@ class RoomMemberHandler(BaseHandler):
         defer.returnValue(room_ids)
 
     @defer.inlineCallbacks
-    def _do_local_membership_update(self, event, membership, snapshot,
+    def _do_local_membership_update(self, event, membership, context,
                                     do_auth):
         yield run_on_reactor()
 
@@ -543,9 +519,9 @@ class RoomMemberHandler(BaseHandler):
         else:
             do_invite_host = None
 
-        yield self._on_new_room_event(
+        yield self.handle_new_client_event(
             event,
-            snapshot,
+            context,
             extra_users=[target_user],
             suppress_auth=(not do_auth),
             do_invite_host=do_invite_host,
diff --git a/synapse/rest/base.py b/synapse/rest/base.py
index 79fc4dfb8..72bb66ddd 100644
--- a/synapse/rest/base.py
+++ b/synapse/rest/base.py
@@ -63,7 +63,7 @@ class RestServlet(object):
         self.hs = hs
 
         self.handlers = hs.get_handlers()
-        self.event_factory = hs.get_event_factory()
+        self.builder_factory = hs.get_event_builder_factory()
         self.auth = hs.get_auth()
         self.txns = HttpTransactionStore()
 
diff --git a/synapse/rest/room.py b/synapse/rest/room.py
index 3147d7a60..3d78b4ff5 100644
--- a/synapse/rest/room.py
+++ b/synapse/rest/room.py
@@ -117,10 +117,10 @@ class RoomStateEventRestServlet(RestServlet):
                                   self.on_PUT_no_state_key)
 
     def on_GET_no_state_key(self, request, room_id, event_type):
-        return self.on_GET(request, room_id, event_type, "")
+        return self.on_GET(request, room_id, event_type, None)
 
     def on_PUT_no_state_key(self, request, room_id, event_type):
-        return self.on_PUT(request, room_id, event_type, "")
+        return self.on_PUT(request, room_id, event_type, None)
 
     @defer.inlineCallbacks
     def on_GET(self, request, room_id, event_type, state_key):
@@ -147,28 +147,18 @@ class RoomStateEventRestServlet(RestServlet):
 
         content = _parse_json(request)
 
-        event = self.event_factory.create_event(
-            etype=event_type,  # already urldecoded
-            content=content,
-            room_id=urllib.unquote(room_id),
-            user_id=user.to_string(),
-            state_key=urllib.unquote(state_key)
-            )
+        msg_handler = self.handlers.message_handler
+        yield msg_handler.handle_event(
+            {
+                "type": event_type,
+                "content": content,
+                "room_id": room_id,
+                "sender": user.to_string(),
+                "state_key": urllib.unquote(state_key),
+            }
+        )
 
-        self.validator.validate(event)
-
-        if event_type == RoomMemberEvent.TYPE:
-            # membership events are special
-            handler = self.handlers.room_member_handler
-            yield handler.change_membership(event)
-            defer.returnValue((200, {}))
-        else:
-            # store random bits of state
-            msg_handler = self.handlers.message_handler
-            yield msg_handler.store_room_data(
-                event=event
-            )
-            defer.returnValue((200, {}))
+        defer.returnValue((200, {}))
 
 
 # TODO: Needs unit testing for generic events + feedback
@@ -184,17 +174,15 @@ class RoomSendEventRestServlet(RestServlet):
         user = yield self.auth.get_user_by_req(request)
         content = _parse_json(request)
 
-        event = self.event_factory.create_event(
-            etype=urllib.unquote(event_type),
-            room_id=urllib.unquote(room_id),
-            user_id=user.to_string(),
-            content=content
-        )
-
-        self.validator.validate(event)
-
         msg_handler = self.handlers.message_handler
-        yield msg_handler.send_message(event)
+        event = yield msg_handler.handle_event(
+            {
+                "type": urllib.unquote(event_type),
+                "content": content,
+                "room_id": urllib.unquote(room_id),
+                "sender": user.to_string(),
+            }
+        )
 
         defer.returnValue((200, {"event_id": event.event_id}))
 
@@ -251,18 +239,17 @@ class JoinRoomAliasServlet(RestServlet):
             ret_dict = yield handler.join_room_alias(user, identifier)
             defer.returnValue((200, ret_dict))
         else:  # room id
-            event = self.event_factory.create_event(
-                etype=RoomMemberEvent.TYPE,
-                content={"membership": Membership.JOIN},
-                room_id=urllib.unquote(identifier.to_string()),
-                user_id=user.to_string(),
-                state_key=user.to_string()
+            msg_handler = self.handlers.message_handler
+            yield msg_handler.handle_event(
+                {
+                    "type": RoomMemberEvent.TYPE,
+                    "content": {"membership": Membership.JOIN},
+                    "room_id": urllib.unquote(identifier.to_string()),
+                    "sender": user.to_string(),
+                    "state_key": user.to_string(),
+                }
             )
 
-            self.validator.validate(event)
-
-            handler = self.handlers.room_member_handler
-            yield handler.change_membership(event)
             defer.returnValue((200, {}))
 
     @defer.inlineCallbacks
@@ -414,18 +401,17 @@ class RoomMembershipRestServlet(RestServlet):
             if membership_action == "kick":
                 membership_action = "leave"
 
-        event = self.event_factory.create_event(
-            etype=RoomMemberEvent.TYPE,
-            content={"membership": unicode(membership_action)},
-            room_id=urllib.unquote(room_id),
-            user_id=user.to_string(),
-            state_key=state_key
+        msg_handler = self.handlers.message_handler
+        yield msg_handler.handle_event(
+            {
+                "type": RoomMemberEvent.TYPE,
+                "content": {"membership": unicode(membership_action)},
+                "room_id": urllib.unquote(room_id),
+                "sender": user.to_string(),
+                "state_key": state_key,
+            }
         )
 
-        self.validator.validate(event)
-
-        handler = self.handlers.room_member_handler
-        yield handler.change_membership(event)
         defer.returnValue((200, {}))
 
     @defer.inlineCallbacks
@@ -453,18 +439,16 @@ class RoomRedactEventRestServlet(RestServlet):
         user = yield self.auth.get_user_by_req(request)
         content = _parse_json(request)
 
-        event = self.event_factory.create_event(
-            etype=RoomRedactionEvent.TYPE,
-            room_id=urllib.unquote(room_id),
-            user_id=user.to_string(),
-            content=content,
-            redacts=urllib.unquote(event_id),
-        )
-
-        self.validator.validate(event)
-
         msg_handler = self.handlers.message_handler
-        yield msg_handler.send_message(event)
+        event = yield msg_handler.handle_event(
+            {
+                "type": RoomRedactionEvent.TYPE,
+                "content": content,
+                "room_id": urllib.unquote(room_id),
+                "sender": user.to_string(),
+                "redacts": urllib.unquote(event_id),
+            }
+        )
 
         defer.returnValue((200, {"event_id": event.event_id}))
 
diff --git a/synapse/server.py b/synapse/server.py
index c3b54221d..8bc27bbc3 100644
--- a/synapse/server.py
+++ b/synapse/server.py
@@ -36,6 +36,7 @@ from synapse.util.lockutils import LockManager
 from synapse.streams.events import EventSources
 from synapse.api.ratelimiting import Ratelimiter
 from synapse.crypto.keyring import Keyring
+from synapse.events.builder import EventBuilderFactory
 
 
 class BaseHomeServer(object):
@@ -82,6 +83,7 @@ class BaseHomeServer(object):
         'ratelimiter',
         'keyring',
         'event_validator',
+        'event_builder_factory',
     ]
 
     def __init__(self, hostname, **kwargs):
@@ -231,6 +233,12 @@ class HomeServer(BaseHomeServer):
     def build_event_validator(self):
         return EventValidator(self)
 
+    def build_event_builder_factory(self):
+        return EventBuilderFactory(
+            clock=self.get_clock(),
+            hostname=self.hostname,
+        )
+
     def register_servlets(self):
         """ Register all servlets associated with this HomeServer.
         """
diff --git a/synapse/storage/signatures.py b/synapse/storage/signatures.py
index e2f11c7ff..3a705119f 100644
--- a/synapse/storage/signatures.py
+++ b/synapse/storage/signatures.py
@@ -13,6 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from twisted.internet import defer
+
 from _base import SQLBaseStore
 
 from syutil.base64util import encode_base64
@@ -69,8 +71,9 @@ class SignatureStore(SQLBaseStore):
             f
         )
 
+    @defer.inlineCallbacks
     def add_event_hashes(self, event_ids):
-        hashes = yield self.store.get_event_reference_hashes(
+        hashes = yield self.get_event_reference_hashes(
             event_ids
         )
         hashes = [