diff --git a/pytket/docs/changelog.rst b/pytket/docs/changelog.rst
index 2923bf2b8c..54d605a629 100644
--- a/pytket/docs/changelog.rst
+++ b/pytket/docs/changelog.rst
@@ -4,6 +4,10 @@ Changelog
 Unreleased
 ----------
 
+API changes:
+
+* Make the ``architecture`` field in ``BackendInfo`` optional.
+
 Deprecations:
 
 * Deprecate ``SynthesiseHQS`` pass.