diff --git a/CHANGELOG.md b/CHANGELOG.md
index 470bf39d..5822630a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # [unreleased]
 
+Breaking changes:
+
+* Update unsigned field's type from `Option<Value>` to `Map<String, Value>`
+
 Improvements:
 
 * Add a convenience constructor to create a plain-text `TextMessageEventContent`