diff --git a/HISTORY.rst b/HISTORY.rst
index b7cc4e0..4119a1e 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -3,6 +3,15 @@
 History
 -------
 
+3.9 (2024-09-13)
+++++++++++++++++
+
+- Update to Unicode 16.0.0
+- Deprecate setup.cfg in favour of pyproject.toml
+- Use ruff for code formatting
+
+Thanks to Waket Zheng for contributions to this release.
+
 3.8 (2024-08-23)
 ++++++++++++++++
 
diff --git a/idna/package_data.py b/idna/package_data.py
index 4c9dba5..ddd1e69 100644
--- a/idna/package_data.py
+++ b/idna/package_data.py
@@ -1 +1 @@
-__version__ = "3.8"
+__version__ = "3.9"