diff --git a/synapse/events/utils.py b/synapse/events/utils.py
index bcb5457278..e391aca4cc 100644
--- a/synapse/events/utils.py
+++ b/synapse/events/utils.py
@@ -89,31 +89,31 @@ def prune_event(event):
     return type(event)(allowed_fields)
 
 
-def serialize_event(hs, e, client_event=True):
+def serialize_event(e, time_now_ms, client_event=True):
     # FIXME(erikj): To handle the case of presence events and the like
     if not isinstance(e, EventBase):
         return e
 
+    time_now_ms = int(time_now_ms)
+
     # Should this strip out None's?
     d = {k: v for k, v in e.get_dict().items()}
 
     if not client_event:
         # set the age and keep all other keys
         if "age_ts" in d["unsigned"]:
-            now = int(hs.get_clock().time_msec())
-            d["unsigned"]["age"] = now - d["unsigned"]["age_ts"]
+            d["unsigned"]["age"] = time_now_ms - d["unsigned"]["age_ts"]
         return d
 
     if "age_ts" in d["unsigned"]:
-        now = int(hs.get_clock().time_msec())
-        d["age"] = now - d["unsigned"]["age_ts"]
+        d["age"] = time_now_ms - d["unsigned"]["age_ts"]
         del d["unsigned"]["age_ts"]
 
     d["user_id"] = d.pop("sender", None)
 
     if "redacted_because" in e.unsigned:
         d["redacted_because"] = serialize_event(
-            hs, e.unsigned["redacted_because"]
+            e.unsigned["redacted_because"], time_now_ms
         )
 
         del d["unsigned"]["redacted_because"]
diff --git a/synapse/handlers/events.py b/synapse/handlers/events.py
index 01e67b0818..d997917cd6 100644
--- a/synapse/handlers/events.py
+++ b/synapse/handlers/events.py
@@ -18,6 +18,7 @@ from twisted.internet import defer
 from synapse.util.logcontext import PreserveLoggingContext
 from synapse.util.logutils import log_function
 from synapse.types import UserID
+from synapse.events.utils import serialize_event
 
 from ._base import BaseHandler
 
@@ -78,8 +79,10 @@ class EventStreamHandler(BaseHandler):
                     auth_user, room_ids, pagin_config, timeout
                 )
 
+            time_now = self.clock.time_msec()
+
             chunks = [
-                self.hs.serialize_event(e, as_client_event) for e in events
+                serialize_event(e, time_now, as_client_event) for e in events
             ]
 
             chunk = {
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 6a1104a890..9c3271fe88 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -18,6 +18,7 @@ from twisted.internet import defer
 from synapse.api.constants import EventTypes, Membership
 from synapse.api.errors import RoomError
 from synapse.streams.config import PaginationConfig
+from synapse.events.utils import serialize_event
 from synapse.events.validator import EventValidator
 from synapse.util.logcontext import PreserveLoggingContext
 from synapse.types import UserID
@@ -100,9 +101,11 @@ class MessageHandler(BaseHandler):
             "room_key", next_key
         )
 
+        time_now = self.clock.time_msec()
+
         chunk = {
             "chunk": [
-                self.hs.serialize_event(e, as_client_event) for e in events
+                serialize_event(e, time_now, as_client_event) for e in events
             ],
             "start": pagin_config.from_token.to_string(),
             "end": next_token.to_string(),
@@ -211,7 +214,8 @@ class MessageHandler(BaseHandler):
 
         # TODO: This is duplicating logic from snapshot_all_rooms
         current_state = yield self.state_handler.get_current_state(room_id)
-        defer.returnValue([self.hs.serialize_event(c) for c in current_state])
+        now = self.clock.time_msec()
+        defer.returnValue([serialize_event(c, now) for c in current_state])
 
     @defer.inlineCallbacks
     def snapshot_all_rooms(self, user_id=None, pagin_config=None,
@@ -283,10 +287,11 @@ class MessageHandler(BaseHandler):
 
                 start_token = now_token.copy_and_replace("room_key", token[0])
                 end_token = now_token.copy_and_replace("room_key", token[1])
+                time_now = self.clock.time_msec()
 
                 d["messages"] = {
                     "chunk": [
-                        self.hs.serialize_event(m, as_client_event)
+                        serialize_event(m, time_now, as_client_event)
                         for m in messages
                     ],
                     "start": start_token.to_string(),
@@ -297,7 +302,8 @@ class MessageHandler(BaseHandler):
                     event.room_id
                 )
                 d["state"] = [
-                    self.hs.serialize_event(c) for c in current_state
+                    serialize_event(c, time_now, as_client_event)
+                    for c in current_state
                 ]
             except:
                 logger.exception("Failed to get snapshot")
@@ -320,8 +326,9 @@ class MessageHandler(BaseHandler):
         auth_user = UserID.from_string(user_id)
 
         # TODO: These concurrently
+        time_now = self.clock.time_msec()
         state_tuples = yield self.state_handler.get_current_state(room_id)
-        state = [self.hs.serialize_event(x) for x in state_tuples]
+        state = [serialize_event(x, time_now) for x in state_tuples]
 
         member_event = (yield self.store.get_room_member(
             user_id=user_id,
@@ -360,11 +367,13 @@ class MessageHandler(BaseHandler):
                     "Failed to get member presence of %r", m.user_id
                 )
 
+        time_now = self.clock.time_msec()
+
         defer.returnValue({
             "membership": member_event.membership,
             "room_id": room_id,
             "messages": {
-                "chunk": [self.hs.serialize_event(m) for m in messages],
+                "chunk": [serialize_event(m, time_now) for m in messages],
                 "start": start_token.to_string(),
                 "end": end_token.to_string(),
             },
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index edb96cec83..23821d321f 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -16,12 +16,14 @@
 """Contains functions for performing events on rooms."""
 from twisted.internet import defer
 
+from ._base import BaseHandler
+
 from synapse.types import UserID, RoomAlias, RoomID
 from synapse.api.constants import EventTypes, Membership, JoinRules
 from synapse.api.errors import StoreError, SynapseError
 from synapse.util import stringutils
 from synapse.util.async import run_on_reactor
-from ._base import BaseHandler
+from synapse.events.utils import serialize_event
 
 import logging
 
@@ -293,8 +295,9 @@ class RoomMemberHandler(BaseHandler):
         yield self.auth.check_joined_room(room_id, user_id)
 
         member_list = yield self.store.get_room_members(room_id=room_id)
+        time_now = self.clock.time_msec()
         event_list = [
-            self.hs.serialize_event(entry)
+            serialize_event(entry, time_now)
             for entry in member_list
         ]
         chunk_data = {
diff --git a/synapse/rest/client/v1/events.py b/synapse/rest/client/v1/events.py
index c69de56863..a0d051227b 100644
--- a/synapse/rest/client/v1/events.py
+++ b/synapse/rest/client/v1/events.py
@@ -19,6 +19,7 @@ from twisted.internet import defer
 from synapse.api.errors import SynapseError
 from synapse.streams.config import PaginationConfig
 from .base import ClientV1RestServlet, client_path_pattern
+from synapse.events.utils import serialize_event
 
 import logging
 
@@ -64,14 +65,19 @@ class EventStreamRestServlet(ClientV1RestServlet):
 class EventRestServlet(ClientV1RestServlet):
     PATTERN = client_path_pattern("/events/(?P<event_id>[^/]*)$")
 
+    def __init__(self, hs):
+        super(EventRestServlet, self).__init__(hs)
+        self.clock = hs.get_clock()
+
     @defer.inlineCallbacks
     def on_GET(self, request, event_id):
         auth_user = yield self.auth.get_user_by_req(request)
         handler = self.handlers.event_handler
         event = yield handler.get_event(auth_user, event_id)
 
+        time_now = self.clock.time_msec()
         if event:
-            defer.returnValue((200, self.hs.serialize_event(event)))
+            defer.returnValue((200, serialize_event(event, time_now)))
         else:
             defer.returnValue((404, "Event not found."))
 
diff --git a/synapse/rest/client/v1/room.py b/synapse/rest/client/v1/room.py
index f06e3ddb98..58b09b6fc1 100644
--- a/synapse/rest/client/v1/room.py
+++ b/synapse/rest/client/v1/room.py
@@ -21,6 +21,7 @@ from synapse.api.errors import SynapseError, Codes
 from synapse.streams.config import PaginationConfig
 from synapse.api.constants import EventTypes, Membership
 from synapse.types import UserID, RoomID, RoomAlias
+from synapse.events.utils import serialize_event
 
 import json
 import logging
@@ -363,6 +364,10 @@ class RoomInitialSyncRestServlet(ClientV1RestServlet):
 class RoomTriggerBackfill(ClientV1RestServlet):
     PATTERN = client_path_pattern("/rooms/(?P<room_id>[^/]*)/backfill$")
 
+    def __init__(self, hs):
+        super(RoomTriggerBackfill, self).__init__(hs)
+        self.clock = hs.get_clock()
+
     @defer.inlineCallbacks
     def on_GET(self, request, room_id):
         remote_server = urllib.unquote(
@@ -374,7 +379,9 @@ class RoomTriggerBackfill(ClientV1RestServlet):
         handler = self.handlers.federation_handler
         events = yield handler.backfill(remote_server, room_id, limit)
 
-        res = [self.hs.serialize_event(event) for event in events]
+        time_now = self.clock.time_msec()
+
+        res = [serialize_event(event, time_now) for event in events]
         defer.returnValue((200, res))
 
 
diff --git a/synapse/server.py b/synapse/server.py
index 92ed2c5e32..c478f812e6 100644
--- a/synapse/server.py
+++ b/synapse/server.py
@@ -124,9 +124,6 @@ class BaseHomeServer(object):
 
         setattr(BaseHomeServer, "get_%s" % (depname), _get)
 
-    def serialize_event(self, e, as_client_event=True):
-        return serialize_event(self, e, as_client_event)
-
     def get_ip_from_request(self, request):
         # May be an X-Forwarding-For header depending on config
         ip_addr = request.getClientIP()