diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index cb6c100d4..c6c54c71d 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -64,6 +64,7 @@ jobs:
       with:
         github-token: ${{ secrets.github_token }}
         flag-name: ubuntu-${{ matrix.ubuntu }}-ruby-${{ matrix.ruby }}
+        format: lcov
         parallel: true
   finish:
     name: Finalise