diff --git a/doc/setup.md b/doc/setup.md
index 65d7aa2..61c093b 100644
--- a/doc/setup.md
+++ b/doc/setup.md
@@ -38,6 +38,7 @@ location /socket {
 	proxy_http_version 1.1;
 	proxy_set_header Upgrade $http_upgrade;
 	proxy_set_header Connection "Upgrade";
+	proxy_set_header Host $host;
 	proxy_set_header X-Forwarded-For $remote_addr;
 	proxy_set_header X-Forwarded-Proto $scheme;
 }