diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6db5dbae..867bbafa 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -13,6 +13,7 @@ concurrency:
 
 env:
   POETRY_VIRTUALENVS_IN_PROJECT: "true"
+  UV_PYTHON_PREFERENCE: only-managed  # avoid ancient system Python
 
 jobs:
   lint: