diff --git a/CHANGELOG.md b/CHANGELOG.md
index 02c5790..4844c02 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,11 @@
 
 ## [Unreleased]
 
+### Changed
+
+- the `Serialize` impl of the `Insertion` type now produce 3-4x smaller
+  payloads, depending on the data format used ([#5](https://github.com/nomad/cola/pull/5));
+
 ## [0.3.0] - Jan 9 2024
 
 ### Added