diff --git a/docs/setup.md b/docs/setup.md
index c0f1ec114..642da4213 100644
--- a/docs/setup.md
+++ b/docs/setup.md
@@ -881,6 +881,7 @@ http {
             proxy_set_header X-Real-IP $remote_addr;
             proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
             proxy_set_header X-Forwarded-Host $server_name;
+            add_header P3P 'CP=""'; # may not be required in all setups
         }
     }
 }