diff --git a/admin/doorman/storage/classes.py b/admin/doorman/storage/classes.py
index 113b2e8..84bcb47 100644
--- a/admin/doorman/storage/classes.py
+++ b/admin/doorman/storage/classes.py
@@ -1,5 +1,5 @@
 from sys import stderr
-from collections import MutableMapping
+from collections.abc import MutableMapping
 from io import StringIO
 
 import csv, json
@@ -12,7 +12,7 @@ class Storage(MutableMapping):
     def sync(self):
         self.encapsulation.data = self.encode(self.data)
         self.encapsulation.end_transaction()
-        
+
         self.encapsulation.begin_transaction()
     def __setitem__(self, k, v):
         self.data[k] = v
@@ -30,7 +30,7 @@ class Storage(MutableMapping):
 class CsvStorage(Storage):
     def decode(self, text):
         try:
-            stored = {x[0]: [x[1], x[2]] 
+            stored = {x[0]: [x[1], x[2]]
                 for x in csv.reader(StringIO(text))}
         except IOError as e:
             print(e, file=stderr)
@@ -52,4 +52,3 @@ class JsonStorage(Storage):
         return stored
     def encode(self, data):
         return json.dumps(data, indent=4)
-