diff --git a/changelogs/client_server/newsfragments/2519.clarification b/changelogs/client_server/newsfragments/2519.clarification
new file mode 100644
index 00000000..eb3fb6a8
--- /dev/null
+++ b/changelogs/client_server/newsfragments/2519.clarification
@@ -0,0 +1 @@
+Fix the ``.m.rule.contains_user_name`` default push rule to set the highlight tweak, matching Synapse and users' expectations.
diff --git a/specification/modules/push.rst b/specification/modules/push.rst
index c9489987..ebf1aef2 100644
--- a/specification/modules/push.rst
+++ b/specification/modules/push.rst
@@ -473,6 +473,9 @@ Definition (as a ``content`` rule):
             {
                 "set_tweak": "sound",
                 "value": "default"
+            },
+            {
+                "set_tweak": "highlight"
             }
         ]
     }