diff --git a/transport/internet/splithttp/hub.go b/transport/internet/splithttp/hub.go
index 5181b19bcf73..18aeb9ca095f 100644
--- a/transport/internet/splithttp/hub.go
+++ b/transport/internet/splithttp/hub.go
@@ -162,6 +162,8 @@ func (h *requestHandler) ServeHTTP(writer http.ResponseWriter, request *http.Req
 		// magic header instructs nginx + apache to not buffer response body
 		writer.Header().Set("X-Accel-Buffering", "no")
 		writer.WriteHeader(http.StatusOK)
+		// magic header for cloudflared tunnel
+		writer.Header().Set("Content-Type", "text/event-stream")
 		// send a chunk immediately to enable CDN streaming.
 		// many CDN buffer the response headers until the origin starts sending
 		// the body, with no way to turn it off.