diff --git a/.github/workflows/pytest.yml b/.github/workflows/pytest.yml
index a4c27116..af98e210 100644
--- a/.github/workflows/pytest.yml
+++ b/.github/workflows/pytest.yml
@@ -43,4 +43,4 @@ jobs:
           uv pip freeze --system
 
       - name: Run tests
-        run: pytest --cov=pyerrors -vv
+        run: pytest --cov=pyerrors -vv -Werror