diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index d3352bdd..8df86609 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -1,3 +1,12 @@
+v4.17.2
+=======
+
+* Empty strings are not valid relative JSON Pointers (aren't valid under the
+  RJP format).
+* Durations without (trailing) units are not valid durations (aren't
+  valid under the duration format). This involves changing the dependency
+  used for validating durations (from ``isoduration`` to ``isodate``).
+
 v4.17.1
 =======
 
diff --git a/jsonschema/_format.py b/jsonschema/_format.py
index 5e483269..5ec97977 100644
--- a/jsonschema/_format.py
+++ b/jsonschema/_format.py
@@ -501,7 +501,9 @@ def is_uri_template(instance: object) -> bool:
     def is_duration(instance: object) -> bool:
         if not isinstance(instance, str):
             return True
-        return bool(isoduration.parse_duration(instance))
+        isoduration.parse_duration(instance)
+        # FIXME: See bolsote/isoduration#25 and bolsote/isoduration#21
+        return instance.endswith(tuple("DMYWHMS"))
 
 
 @_checks_drafts(