diff --git a/livereload/server.py b/livereload/server.py
index ec4e6f1..e6d8d8e 100644
--- a/livereload/server.py
+++ b/livereload/server.py
@@ -125,7 +125,7 @@ def start_response(status, response_headers, exc_info=None):
             return response.append
 
         app_response = self.wsgi_app(
-            WSGIContainer.environ(request), start_response)
+            WSGIContainer(self.wsgi_app).environ(request), start_response)
         try:
             response.extend(app_response)
             body = b"".join(response)