diff --git a/django/core/cache/backends/redis.py b/django/core/cache/backends/redis.py
index eda8ac9457..bbf070a375 100644
--- a/django/core/cache/backends/redis.py
+++ b/django/core/cache/backends/redis.py
@@ -14,8 +14,9 @@ class RedisSerializer:
         self.protocol = pickle.HIGHEST_PROTOCOL if protocol is None else protocol
 
     def dumps(self, obj):
-        # Only skip pickling for integers, a int subclasses as bool should be
-        # pickled.
+        # For better incr() and decr() atomicity, don't pickle integers.
+        # Using type() rather than isinstance() matches only integers and not
+        # subclasses like bool.
         if type(obj) is int:
             return obj
         return pickle.dumps(obj, self.protocol)