diff --git a/tests/scenario/conftest.py b/tests/scenario/conftest.py
index f40f72d..d22d87f 100644
--- a/tests/scenario/conftest.py
+++ b/tests/scenario/conftest.py
@@ -15,7 +15,7 @@ def coordinator():
 @pytest.fixture
 def tempo_charm():
     with patch("lightkube.core.client.GenericSyncClient"):
-        with patch.object(Nginx, "are_certificates_on_disk", False):
+        with patch("charm.TempoCoordinatorCharm.are_certificates_on_disk", False):
             yield TempoCoordinatorCharm