diff --git a/pytools/persistent_dict.py b/pytools/persistent_dict.py
index a42ab6353472592e823d24d4dbf5dbdb07bcedaf..4836d7f3775de4b321803130c3868f5bcd738bd5 100644
--- a/pytools/persistent_dict.py
+++ b/pytools/persistent_dict.py
@@ -272,6 +272,11 @@ class KeyBuilder:
 
     # {{{ updaters
 
+    @staticmethod
+    def update_for_type(key_hash, key):
+        key_hash.update(
+            f"{key.__module__}.{key.__qualname__}.{key.__name__}".encode("utf-8"))
+
     @staticmethod
     def update_for_int(key_hash, key):
         sz = 8