diff --git a/data/conf/nginx/includes/site-defaults.conf b/data/conf/nginx/includes/site-defaults.conf
index ec47a544..2f124807 100644
--- a/data/conf/nginx/includes/site-defaults.conf
+++ b/data/conf/nginx/includes/site-defaults.conf
@@ -13,7 +13,7 @@
   ssl_session_timeout 1d;
   ssl_session_tickets off;
 
-  add_header Strict-Transport-Security "max-age=15768000; includeSubDomains; preload";
+  add_header Strict-Transport-Security "max-age=15768000; preload";
   add_header X-Content-Type-Options nosniff;
   add_header X-XSS-Protection "0";
   add_header X-Robots-Tag none;