diff --git a/tests/run.py b/tests/run.py
index 786e99bd..477a3735 100755
--- a/tests/run.py
+++ b/tests/run.py
@@ -69,6 +69,7 @@ def run_eval_test(gcroot_dir: Path, jobs: int) -> list[str]:
     failed_profiles = []
     cmd = [
         "nix-eval-jobs",
+        "--no-instantiate",
         "--extra-experimental-features", "flakes",
         "--option", "eval-cache", "false",
         "--gc-roots-dir",