diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 97a81b7c..958faa67 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -17,6 +17,7 @@ jobs:
         # in __init__. below we'll reinstall for the tests.
         run: |
           pip install astropy
+          pip install frank
           pip install .
       - name: Cache/Restore the .mpol folder cache
         uses: actions/cache@v3