diff --git a/apns.py b/apns.py
index 906fdee..60a991d 100644
--- a/apns.py
+++ b/apns.py
@@ -556,6 +556,8 @@ def _make_sure_error_response_handler_worker_alive(self):
             _logger.warning("error response handler worker is not started after %s secs" % TIMEOUT_SEC)
 
     def send_notification_multiple(self, frame):
+        if self.enhanced:
+            self._make_sure_error_response_handler_worker_alive()
         self._sent_notifications += frame.get_notifications(self)
         return self.write(frame.get_frame())