diff --git a/synapse/api/auth.py b/synapse/api/auth.py
index 847ff60671..e3b8c3099a 100644
--- a/synapse/api/auth.py
+++ b/synapse/api/auth.py
@@ -20,7 +20,7 @@ from twisted.internet import defer
 from synapse.api.constants import EventTypes, Membership, JoinRules
 from synapse.api.errors import AuthError, Codes, SynapseError
 from synapse.util.logutils import log_function
-from synapse.types import UserID, EventID
+from synapse.types import RoomID, UserID, EventID
 
 import logging
 import pymacaroons
@@ -80,6 +80,15 @@ class Auth(object):
                     "Room %r does not exist" % (event.room_id,)
                 )
 
+            creating_domain = RoomID.from_string(event.room_id).domain
+            originating_domain = UserID.from_string(event.sender).domain
+            if creating_domain != originating_domain:
+                if not self.can_federate(event, auth_events):
+                    raise AuthError(
+                        403,
+                        "This room has been marked as unfederatable."
+                    )
+
             # FIXME: Temp hack
             if event.type == EventTypes.Aliases:
                 return True
@@ -219,6 +228,11 @@ class Auth(object):
                 user_id, room_id, repr(member)
             ))
 
+    def can_federate(self, event, auth_events):
+        creation_event = auth_events.get((EventTypes.Create, ""))
+
+        return creation_event.content.get("m.federate", True) is True
+
     @log_function
     def is_membership_change_allowed(self, event, auth_events):
         membership = event.content["membership"]
@@ -234,6 +248,15 @@ class Auth(object):
 
         target_user_id = event.state_key
 
+        creating_domain = RoomID.from_string(event.room_id).domain
+        target_domain = UserID.from_string(target_user_id).domain
+        if creating_domain != target_domain:
+            if not self.can_federate(event, auth_events):
+                raise AuthError(
+                    403,
+                    "This room has been marked as unfederatable."
+                )
+
         # get info about the caller
         key = (EventTypes.Member, event.user_id, )
         caller = auth_events.get(key)
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index b677955523..ac636255c2 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -149,12 +149,15 @@ class RoomCreationHandler(BaseHandler):
         for val in raw_initial_state:
             initial_state[(val["type"], val.get("state_key", ""))] = val["content"]
 
+        creation_content = config.get("creation_content", {})
+
         user = UserID.from_string(user_id)
         creation_events = self._create_events_for_new_room(
             user, room_id,
             preset_config=preset_config,
             invite_list=invite_list,
             initial_state=initial_state,
+            creation_content=creation_content,
             room_alias=room_alias,
         )
 
@@ -203,7 +206,8 @@ class RoomCreationHandler(BaseHandler):
         defer.returnValue(result)
 
     def _create_events_for_new_room(self, creator, room_id, preset_config,
-                                    invite_list, initial_state, room_alias):
+                                    invite_list, initial_state, creation_content,
+                                    room_alias):
         config = RoomCreationHandler.PRESETS_DICT[preset_config]
 
         creator_id = creator.to_string()
@@ -225,9 +229,10 @@ class RoomCreationHandler(BaseHandler):
 
             return e
 
+        creation_content.update({"creator": creator.to_string()})
         creation_event = create(
             etype=EventTypes.Create,
-            content={"creator": creator.to_string()},
+            content=creation_content,
         )
 
         join_event = create(
diff --git a/tests/test_state.py b/tests/test_state.py
index 55f37c521f..0274c4bc18 100644
--- a/tests/test_state.py
+++ b/tests/test_state.py
@@ -35,7 +35,7 @@ def create_event(name=None, type=None, state_key=None, depth=2, event_id=None,
 
     if not event_id:
         _next_event_id += 1
-        event_id = str(_next_event_id)
+        event_id = "$%s:test" % (_next_event_id,)
 
     if not name:
         if state_key is not None: