diff --git a/CHANGELOG.md b/CHANGELOG.md
index ec4a08dc..bc1afb68 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## Unreleased
+
+**Features**:
+
+- Users of `TransactionContext` may now add `custom` context to it. This may be used by `traces_sampler` to decide sampling rates on a per-transaction basis. ([#512](https://github.com/getsentry/sentry-rust/pull/512))
+
 ## 0.28.0
 
 **Breaking Changes**: