diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8cb40ad1..b47cfd52 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ### Added
 - Support for Paeth PNG filter compression (predictor value = 4) ([#537](https://github.com/pdfminer/pdfminer.six/pull/537))
+- Type annotations for core modules ([#661](https://github.com/pdfminer/pdfminer.six/pull/661))
 
 ### Fixed
 - `KeyError` when `'Encrypt'` but not `'ID'` present in `trailer` ([#594](https://github.com/pdfminer/pdfminer.six/pull/594))