diff --git a/changelog.d/12939.bugfix b/changelog.d/12939.bugfix
new file mode 100644
index 000000000000..d9061cf8e548
--- /dev/null
+++ b/changelog.d/12939.bugfix
@@ -0,0 +1 @@
+Update [MSC3786](https://github.com/matrix-org/matrix-spec-proposals/pull/3786) implementation to check `state_key`.
diff --git a/synapse/push/baserules.py b/synapse/push/baserules.py
index 819bc9e9b680..6c0cc5a6ce82 100644
--- a/synapse/push/baserules.py
+++ b/synapse/push/baserules.py
@@ -290,7 +290,13 @@ def make_base_prepend_rules(
                 "key": "type",
                 "pattern": "m.room.server_acl",
                 "_cache_key": "_room_server_acl",
-            }
+            },
+            {
+                "kind": "event_match",
+                "key": "state_key",
+                "pattern": "",
+                "_cache_key": "_room_server_acl_state_key",
+            },
         ],
         "actions": [],
     },