diff --git a/CHANGELOG_PENDING.md b/CHANGELOG_PENDING.md
index 8a1927a39c..27400f5b6c 100644
--- a/CHANGELOG_PENDING.md
+++ b/CHANGELOG_PENDING.md
@@ -1,5 +1,6 @@
 ### SDK Features
 
 ### SDK Enhancements
+* `private/protocol`: The SDK now supports the serialization of ISO8601 date-time formats with fractional seconds precision. ([#3489](https://github.com/aws/aws-sdk-go/pull/3489))
 
 ### SDK Bugs