diff --git a/src/mahjong_ranking/middleware.py b/src/mahjong_ranking/middleware.py
index 2b71256..c93909a 100644
--- a/src/mahjong_ranking/middleware.py
+++ b/src/mahjong_ranking/middleware.py
@@ -1,12 +1,26 @@
 """Middleware to defer slow denormalization  at the end of a request."""
 from django.core.cache import cache
+
 from mahjong_ranking import models
 from . import LOGGER
+from . import LOGGER
 
-
-class DenormalizationUpdateMiddleware(object):  # Ignore PyLintBear (R0903)
+class DenormalizationUpdateMiddleware:
     """To recalculate everything in the queues at the end of a POST request."""
 
+    def __init__(self, get_response=None):
+        self.get_response = get_response
+        super().__init__()
+
+    def __call__(self, request):
+        response = None
+        if hasattr(self, 'process_request'):
+            response = self.process_request(request)
+        response = response or self.get_response(request)
+        if hasattr(self, 'process_response'):
+            response = self.process_response(request, response)
+        return response
+
     def process_response(self, request, response):  # Ignore PyLintBear (R0201)
         """Check and process the recalculation queues on each POST request.
 
@@ -16,7 +30,6 @@ class DenormalizationUpdateMiddleware(object):  # Ignore PyLintBear (R0903)
         """
         event_queue = set()
         season_queue = set()
-
         if request.method != 'POST':
             return response