diff --git a/CHANGELOG.md b/CHANGELOG.md
index c4154223..1c29b408 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,5 +21,6 @@ We use *breaking :warning:* to mark changes that are not backward compatible (re
 
 ### Changed
 - [#38](https://github.com/thanos-io/objstore/pull/38) *: Upgrade minio-go version to `v7.0.45`.
+- [#39](https://github.com/thanos-io/objstore/pull/39) COS: Upgrade cos sdk version to `v0.7.40`.
 
 ### Removed