diff --git a/nix/modules/hive-matrix.nix b/nix/modules/hive-matrix.nix
index 25da87a9..e20175b6 100644
--- a/nix/modules/hive-matrix.nix
+++ b/nix/modules/hive-matrix.nix
@@ -8,12 +8,7 @@ let
   cfg = config.hyperhive.matrix;
   hyperhiveDomain = config.hyperhive.domain;
   effectiveServerName =
-    if cfg.serverName != null then
-      cfg.serverName
-    else if cfg.useSubdomain then
-      "matrix.${hyperhiveDomain}"
-    else
-      hyperhiveDomain;
+    if cfg.serverName != null then cfg.serverName else "matrix.${hyperhiveDomain}";
 in
 {
   # Private Matrix homeserver (matrix-tuwunel — the official conduwuit
@@ -64,29 +59,16 @@ in
     serverName = lib.mkOption {
       type = lib.types.nullOr lib.types.str;
       default = null;
-      example = "matrix.darkest.space";
+      example = "chat.example.org";
       description = ''
         Matrix `server_name` — the host part of every user ID
         (`@argus:<server_name>`) and room ID minted on this
         homeserver. CRITICAL: must be stable from day one because
         it's embedded irrevocably in the identifiers. Defaults to
-        `matrix.''${hyperhive.domain}` when `useSubdomain = true`
-        (the typical path — keeps the root domain free for the
-        dashboard or forge), or to `''${hyperhive.domain}` itself
-        when `useSubdomain = false`. Override here only if you need
-        a name that doesn't follow either pattern.
-      '';
-    };
-
-    useSubdomain = lib.mkOption {
-      type = lib.types.bool;
-      default = true;
-      description = ''
-        When `serverName` is unset, use `matrix.''${hyperhive.domain}`
-        rather than `''${hyperhive.domain}` itself. The default is
-        true because the root domain is usually claimed by the
-        dashboard or the forge; turn off only if the root domain is
-        free AND you want matrix to serve from there.
+        `matrix.''${hyperhive.domain}` (always a subdomain — keeps
+        the root domain free for the dashboard or forge). Override
+        here only if you need a name that doesn't follow the
+        `matrix.<domain>` shape.
       '';
     };