diff --git a/CHANGELOG.md b/CHANGELOG.md
index ea42247..1b95f71 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Follow zoom factor of the parent window in `<iframe>` ([#21](https://github.com/marp-team/marpit-svg-polyfill/pull/21))
+
 ### Changed
 
 - Upgrade development Node LTS ans dependent packages to the latest version ([#22](https://github.com/marp-team/marpit-svg-polyfill/pull/22))