diff --git a/racketmq/hub/websocket.rkt b/racketmq/hub/websocket.rkt
index 2b49c82..ed067a5 100644
--- a/racketmq/hub/websocket.rkt
+++ b/racketmq/hub/websocket.rkt
@@ -16,7 +16,7 @@
        (during (http-listener $host-name $port)
          (during (canonical-baseurl $baseurl)
            (on (web-request-get (id req) (vh host-name port) ("hub" ()))
-               (when (equal? (dict-ref (web-request-header-headers req) 'upgrade #f) "websocket")
+               (when (web-request-header-websocket-upgrade? req)
                  (websocket-subscription id req baseurl))))))
 
 (define (websocket-subscription id req baseurl)