diff --git a/tests/unit/test_req.py b/tests/unit/test_req.py
index 74b9712dc03..545828f8eea 100644
--- a/tests/unit/test_req.py
+++ b/tests/unit/test_req.py
@@ -105,6 +105,7 @@ def _basic_resolver(
                 use_user_site=False,
                 lazy_wheel=False,
                 verbosity=0,
+                legacy_resolver=True,
             )
             yield Resolver(
                 preparer=preparer,