diff --git a/tornado/web.py b/tornado/web.py
index aab8dc19..70bd0113 100644
--- a/tornado/web.py
+++ b/tornado/web.py
@@ -1160,7 +1160,7 @@ class Application(object):
                         args = [unquote(s) for s in match.groups()]
                     break
             if not handler:
-                handler = ErrorHandler(self, request, 404)
+                handler = ErrorHandler(self, request, status_code=404)
 
         # In debug mode, re-compile templates and reload static files on every
         # request so you don't need to restart to see changes