diff --git a/.github/workflows/pytest.yml b/.github/workflows/pytest.yml
index 320e3543..b25c7d17 100644
--- a/.github/workflows/pytest.yml
+++ b/.github/workflows/pytest.yml
@@ -45,4 +45,4 @@ jobs:
           pip freeze
 
       - name: Run tests
-        run: pytest --cov=pyerrors -vv
+        run: pytest --cov=pyerrors -vv -Werror