diff --git a/pylons_app/config/middleware.py b/pylons_app/config/middleware.py
--- a/pylons_app/config/middleware.py
+++ b/pylons_app/config/middleware.py
@@ -51,10 +51,9 @@ def make_app(global_conf, full_stack=Tru
         # Display error documents for 401, 403, 404 status codes (and
         # 500 when debug is disabled)
         if asbool(config['debug']):
-            #don't handle 404, since mercurial does it for us.
-            app = StatusCodeRedirect(app, [400, 401, 403])
+            app = StatusCodeRedirect(app)
         else:
-            app = StatusCodeRedirect(app, [400, 401, 403, 500])
+            app = StatusCodeRedirect(app, [400, 401, 403, 404, 500])
     
     # Establish the Registry for this application
     app = RegistryManager(app)