diff --git a/nixos/modules/services/web-servers/nginx/vhost-options.nix b/nixos/modules/services/web-servers/nginx/vhost-options.nix
index ccf8804943ac..b708f5b3be5c 100644
--- a/nixos/modules/services/web-servers/nginx/vhost-options.nix
+++ b/nixos/modules/services/web-servers/nginx/vhost-options.nix
@@ -99,6 +99,10 @@ with lib;
       description = lib.mdDoc ''
         Host which to proxy requests to if acme challenge is not found. Useful
         if you want multiple hosts to be able to verify the same domain name.
+
+        For example, you could request certificates for the present domain with
+        an acme client that is running on another host, which you would specify
+        here.
       '';
     };