diff --git a/oml/websocket.py b/oml/websocket.py
index e090c20..eeac42b 100644
--- a/oml/websocket.py
+++ b/oml/websocket.py
@@ -18,9 +18,8 @@ class Handler(WebSocketHandler):
 
     def check_origin(self, origin):
         # allow access to websocket from site, installer and loader (local file)
-        return self.request.host in origin \
-            or origin == 'http://127.0.0.1:9842' \
-            or origin == 'null'
+        return self.request.host in origin or \
+            origin in ('http://127.0.0.1:9842', 'null', 'file:///')
 
     def open(self):
         if self.request.headers['origin'] not in ('null', 'http://127.0.0.1:9842') \