diff --git a/src/preflight.rs b/src/preflight.rs
index 06a0c61..ba09afa 100644
--- a/src/preflight.rs
+++ b/src/preflight.rs
@@ -408,9 +408,13 @@ mod tests {
         c.openfut_server_host = "127.0.0.2".into();
         c.ea_hostnames = vec!["localhost".into()];
         c.fifa17_tools_dir = "/nonexistent/openfut-tools".into();
+        // Machine-independence: this counts warnings across every check, so the
+        // game dir must not be a real one. A box with a hook deployed (the game
+        // machine always has one) would otherwise add a drift warning here.
+        c.fifa_game_dir = "/nonexistent/fifa-game-dir".into();
         let checks = run(&c);
         assert_eq!(failures(&checks), 0, "must not be reported as fatal");
-        assert_eq!(warnings(&checks), 1);
+        assert_eq!(warnings(&checks), 1, "{checks:#?}");
     }
 
     #[test]