diff --git a/README.md b/README.md
index 9c46ee0f..9e1045ba 100644
--- a/README.md
+++ b/README.md
@@ -95,10 +95,11 @@ name. No default — subsystems that require it (currently:
 message if it is missing.
 
 Optional: set `hyperhive.matrix.enable = true;` to spin up a private
-[matrix-tuwunel](https://github.com/girlbossceo/conduwuit) homeserver
-in a nixos-container. Requires `hyperhive.domain` to be set first.
-The `server_name` (embedded irrevocably in every user and room ID)
-defaults to `matrix.<domain>`; override with
+[matrix-tuwunel](https://github.com/matrix-construct/tuwunel) homeserver
+in a nixos-container. Requires either `hyperhive.domain` or
+`hyperhive.matrix.serverName` to be set (eval fails with a clear error
+if both are absent). The `server_name` (embedded irrevocably in every
+user and room ID) defaults to `matrix.<domain>`; override with
 `hyperhive.matrix.serverName = "chat.example.com";` if needed. State
 lives at `/var/lib/nixos-containers/hive-matrix/`. Federation is
 enabled with an empty `trusted_servers` list; e2ee is deferred to