diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0ea9d22c8..431e9a678 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,7 @@ IMPROVEMENTS:
   * provider/openstack: Add "personality" support to instance resource [GH-4623]
   * provider/aws: Add support for creating Managed Microsoft Active Directory 
     and Directory Connectors [GH-4388]
+  * provider/aws: Mark some `aws_db_instance` fields as optional [GH-3139]
 
 BUG FIXES: