diff --git a/demo/start.sh b/demo/start.sh
index 4546f27ed8..d647400d39 100755
--- a/demo/start.sh
+++ b/demo/start.sh
@@ -34,7 +34,7 @@ for port in 8080 8081 8082; do
         --tls-dh-params-path "demo/demo.tls.dh" \
         --media-store-path "demo/media_store.$port" \
 		$PARAMS $SYNAPSE_PARAMS \
-		--disable-registration false
+		--enable-registration
 
     python -m synapse.app.homeserver \
         --config-path "demo/etc/$port.config" \
diff --git a/synapse/api/auth.py b/synapse/api/auth.py
index 64f605b962..18f3d117b3 100644
--- a/synapse/api/auth.py
+++ b/synapse/api/auth.py
@@ -486,7 +486,7 @@ class Auth(object):
             send_level = send_level_event.content.get("events", {}).get(
                 event.type
             )
-            if not send_level:
+            if send_level is None:
                 if hasattr(event, "state_key"):
                     send_level = send_level_event.content.get(
                         "state_default", 50