diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000000000000000000000000000000000000..6e40f46b04f6abac5f646d26da8640345abf20d8
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,9 @@
+import os
+
+import pytest
+
+from . import testutil
+
+@pytest.fixture(scope='session', autouse=True)
+def clean_environment():
+    os.environ.pop('CONSERVANCY_REPOSITORY', None)