diff --git a/clientapi/routing/redact.go b/clientapi/routing/redact.go
index 45ab60b43..15b8f430b 100644
--- a/clientapi/routing/redact.go
+++ b/clientapi/routing/redact.go
@@ -41,10 +41,11 @@ type redactResponse struct {
 }
 
 // Redact implements PUT /_matrix/client/r0/rooms/{roomId}/redact/{eventId}/{txnId}
+// and POST /_matrix/client/r0/rooms/{roomId}/redact/{eventId} (mainly for SyTest)
 func Redact(
 	req *http.Request,
 	device *authtypes.Device,
-	roomID, redactedEventID, txnID string,
+	roomID, redactedEventID string, txnID *string,
 	cfg config.Dendrite,
 	queryAPI api.RoomserverQueryAPI,
 	producer *producers.RoomserverProducer,
@@ -127,15 +128,18 @@ func Redact(
 
 	// Send the redaction event
 
-	txnAndDeviceID := api.TransactionID{
-		TransactionID: txnID,
-		DeviceID:      device.ID,
+	var txnAndDeviceID *api.TransactionID
+	if txnID != nil {
+		txnAndDeviceID = &api.TransactionID{
+			TransactionID: *txnID,
+			DeviceID:      device.ID,
+		}
 	}
 
 	// pass the new event to the roomserver and receive the correct event ID
 	// event ID in case of duplicate transaction is discarded
 	eventID, err := producer.SendEvents(
-		req.Context(), []gomatrixserverlib.Event{*e}, cfg.Matrix.ServerName, &txnAndDeviceID,
+		req.Context(), []gomatrixserverlib.Event{*e}, cfg.Matrix.ServerName, txnAndDeviceID,
 	)
 	if err != nil {
 		return httputil.LogThenError(req, err)
diff --git a/clientapi/routing/routing.go b/clientapi/routing/routing.go
index 5e0cc3058..9198b8a3a 100644
--- a/clientapi/routing/routing.go
+++ b/clientapi/routing/routing.go
@@ -164,10 +164,21 @@ func Setup(
 			if err != nil {
 				return util.ErrorResponse(err)
 			}
-			return Redact(req, device, vars["roomID"], vars["eventID"], vars["txnID"],
+			txnID := vars["txnID"]
+			return Redact(req, device, vars["roomID"], vars["eventID"], &txnID,
 				cfg, queryAPI, producer, transactionsCache)
 		}),
 	).Methods(http.MethodPut, http.MethodOptions)
+	r0mux.Handle("/rooms/{roomID}/redact/{eventID}",
+		common.MakeAuthAPI("redact", authData, func(req *http.Request, device *authtypes.Device) util.JSONResponse {
+			vars, err := common.URLDecodeMapValues(mux.Vars(req))
+			if err != nil {
+				return util.ErrorResponse(err)
+			}
+			return Redact(req, device, vars["roomID"], vars["eventID"], nil,
+				cfg, queryAPI, producer, transactionsCache)
+		}),
+	).Methods(http.MethodPost, http.MethodOptions)
 
 	r0mux.Handle("/register", common.MakeExternalAPI("register", func(req *http.Request) util.JSONResponse {
 		return Register(req, accountDB, deviceDB, &cfg)