diff --git a/tests/test_model_ladder.py b/tests/test_model_ladder.py
index e553618..674be9f 100644
--- a/tests/test_model_ladder.py
+++ b/tests/test_model_ladder.py
@@ -266,10 +266,6 @@ class TestBuildAwareBackendOrder:
         with patch.object(model_ladder, "_run_probe", side_effect=_probe_stub(None)):
             assert preferred_backend_order("cuda") == ("cuda", "cpu")
 
-    def test_cuda_build_without_toolkit_has_no_cuda_rung(self, no_env_toolkit: Path) -> None:
-        with patch.object(model_ladder, "_run_probe", side_effect=_probe_stub(None)):
-            assert preferred_backend_order("cuda") == ("cpu",)
-
     def test_cpu_build_is_cpu_only(self) -> None:
         assert preferred_backend_order("cpu") == ("cpu",)
 
diff --git a/tests/test_update_checker.py b/tests/test_update_checker.py
index fd7767d..77daca6 100644
--- a/tests/test_update_checker.py
+++ b/tests/test_update_checker.py
@@ -18,6 +18,12 @@ from vocalinux.utils.update_checker import (
 )
 
 
+@pytest.fixture(autouse=True)
+def _unpackaged_install(monkeypatch):
+    """Keep these tests independent of a packaged marker on the host (ticket #27)."""
+    monkeypatch.setattr("vocalinux.utils.update_checker.is_packaged_install", lambda: False)
+
+
 class TestNormalizeAndCompare:
     def test_normalize_version_strips_v_prefix(self):
         assert normalize_version("v0.15.0") == "0.15.0"