diff --git a/pytools/persistent_dict.py b/pytools/persistent_dict.py
index f4d3bf20b0997b786c8326d9f1c7a242279a42f8..df9f2f5b99cf90d872a2089a1c8831a98fc40d1d 100644
--- a/pytools/persistent_dict.py
+++ b/pytools/persistent_dict.py
@@ -469,7 +469,7 @@ class _PersistentDictBase:
             import appdirs
             container_dir = join(
                     appdirs.user_cache_dir("pytools", "pytools"),
-                    "pdict-v3-{}-py{}".format(
+                    "pdict-v4-{}-py{}".format(
                         identifier,
                         ".".join(str(i) for i in sys.version_info)))