diff --git a/CHANGELOG.md b/CHANGELOG.md
index 802361686..38baff2e2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,9 @@
+## 0.2.0a20 (2025-05-09)
+
+### Fix
+
+- undefined is a rougail object
+
 ## 0.2.0a19 (2025-05-05)
 
 ### Fix
diff --git a/pyproject.toml b/pyproject.toml
index fc2cda436..b1ec3ad0b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ requires = ["flit_core >=3.8.0,<4"]
 
 [project]
 name = "rougail.output_doc"
-version = "0.2.0a19"
+version = "0.2.0a20"
 authors = [{name = "Emmanuel Garette", email = "gnunux@gnunux.info"}]
 readme = "README.md"
 description = "Rougail output doc"
diff --git a/src/rougail/output_doc/__version__.py b/src/rougail/output_doc/__version__.py
index 3c65644a5..532b6824c 100644
--- a/src/rougail/output_doc/__version__.py
+++ b/src/rougail/output_doc/__version__.py
@@ -1 +1 @@
-__version__ = "0.2.0a19"
+__version__ = "0.2.0a20"