diff --git a/CHANGES.md b/CHANGES.md
index 59680092c..303aff74a 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,6 +1,8 @@
 unreleased
 -------------------
 
+- Update changelog to use ISO 8061 date format: YYYY-MM-DD. (#445, @ceastlund)
+
 - Driver: Add `-unused-code-warnings` command-line flag. (#444, @ceastlund)
 
 - Add `?warning` flag to `Deriving.Generator.make`. (#440, @jacksonzou123 via @ceastlund)