diff --git a/changelog.d/14159.feature b/changelog.d/14159.feature
new file mode 100644
index 000000000000..5d0ae16e131b
--- /dev/null
+++ b/changelog.d/14159.feature
@@ -0,0 +1 @@
+Support for thread-specific notifications & receipts ([MSC3771](https://github.com/matrix-org/matrix-spec-proposals/pull/3771) and [MSC3773](https://github.com/matrix-org/matrix-spec-proposals/pull/3773)).
diff --git a/synapse/storage/databases/main/receipts.py b/synapse/storage/databases/main/receipts.py
index 246f78ac1ff5..b04026c21ba9 100644
--- a/synapse/storage/databases/main/receipts.py
+++ b/synapse/storage/databases/main/receipts.py
@@ -416,6 +416,8 @@ def f(txn: LoggingTransaction) -> List[Dict[str, Any]]:
             # {"$foo:bar": { "read": { "@user:host": <receipt> }, .. }, .. }
             event_entry = room_event["content"].setdefault(row["event_id"], {})
             receipt_type = event_entry.setdefault(row["receipt_type"], {})
+            if row["thread_id"]:
+                receipt_type[row["user_id"]]["thread_id"] = row["thread_id"]
 
             receipt_type[row["user_id"]] = db_to_json(row["data"])