diff --git a/nixos/tests/convos.nix b/nixos/tests/convos.nix
index 72275ab390d9..cc0c2e75893c 100644
--- a/nixos/tests/convos.nix
+++ b/nixos/tests/convos.nix
@@ -23,7 +23,7 @@ in
 
   testScript = ''
     machine.wait_for_unit("convos")
-    machine.wait_for_open_port(port)
+    machine.wait_for_open_port(${toString port})
     machine.succeed("journalctl -u convos | grep -q 'Listening at.*${toString port}'")
     machine.succeed("curl -f http://localhost:${toString port}/")
   '';