diff --git a/templates/haproxy.cfg.j2 b/templates/haproxy.cfg.j2
index 58c058a..69826cc 100644
--- a/templates/haproxy.cfg.j2
+++ b/templates/haproxy.cfg.j2
@@ -146,7 +146,7 @@ frontend http
     http-request replace-value Host (.*):.* \1
 
 
-    acl is_websocket hrd_upgrade(WebSocket) -i WebSocket 
+    acl is_websocket hdr(Upgrade) -i WebSocket 
     use_backend dev_itineris_italian_seas_bck if is_websocket
 
 {% if docker_swarm_cluster_portainer_install %}