diff --git a/ops/_private/harness.py b/ops/_private/harness.py
index 898046978..cb7ad9725 100644
--- a/ops/_private/harness.py
+++ b/ops/_private/harness.py
@@ -2914,7 +2914,7 @@ def secret_set(
 
     @classmethod
     def _generate_secret_id(cls) -> str:
-        # Not a proper Juju secrets-style xid, but that's okay
+        # Not a proper Juju secrets identifier, but that's okay
         return f'secret:{uuid.uuid4()}'
 
     def secret_add(
diff --git a/ops/model.py b/ops/model.py
index a2c9cd31a..8ce16998f 100644
--- a/ops/model.py
+++ b/ops/model.py
@@ -1391,8 +1391,7 @@ def id(self) -> str | None:
     def unique_identifier(self) -> str | None:
         """Unique identifier of this secret.
 
-        This is the secret's globally-unique identifier (currently a
-        20-character Xid, for example "9m4e2mr0ui3e8a215n4g").
+        This is the secret's globally-unique identifier (alphanumeric).
 
         Charms should use :attr:`id` (the secret's locator ID) to send
         the secret's ID across relation data, and labels (:attr:`label`) to