diff --git a/docs/docs/the-marten-project/release-notes/0.5.1.md b/docs/docs/the-marten-project/release-notes/0.5.1.md
index 4a1bb7d9e..f57d0b799 100644
--- a/docs/docs/the-marten-project/release-notes/0.5.1.md
+++ b/docs/docs/the-marten-project/release-notes/0.5.1.md
@@ -12,3 +12,4 @@ _Under development._
 * Fix excessive verbosity when running management commands.
 * Fix non-working hash/array methods in templates.
 * Fix an issue where unknown variable exceptions are not raised when accessing unsupported attributes on custom template objects.
+* Make sure the cookie session store always defines an expiry when signing the session data.