diff --git a/django/contrib/admin/views/main.py b/django/contrib/admin/views/main.py
index bc158da80a..85e03f3b75 100644
--- a/django/contrib/admin/views/main.py
+++ b/django/contrib/admin/views/main.py
@@ -1,4 +1,5 @@
 import operator
+from functools import reduce
 
 from django.core.exceptions import SuspiciousOperation, ImproperlyConfigured
 from django.core.paginator import InvalidPage
diff --git a/django/core/exceptions.py b/django/core/exceptions.py
index 201a854a4b..e3d1dc9c7e 100644
--- a/django/core/exceptions.py
+++ b/django/core/exceptions.py
@@ -1,6 +1,7 @@
 """
 Global Django exception and warning classes.
 """
+from functools import reduce
 
 class DjangoRuntimeWarning(RuntimeWarning):
     pass
diff --git a/django/utils/crypto.py b/django/utils/crypto.py
index f826c8a80c..9d6486c601 100644
--- a/django/utils/crypto.py
+++ b/django/utils/crypto.py
@@ -8,6 +8,7 @@ import hashlib
 import binascii
 import operator
 import time
+from functools import reduce
 
 # Use the system PRNG if possible
 import random