diff --git a/.github/workflows/haskell-ci.yml b/.github/workflows/haskell-ci.yml
index f5644d6..93e8ece 100644
--- a/.github/workflows/haskell-ci.yml
+++ b/.github/workflows/haskell-ci.yml
@@ -127,6 +127,7 @@ jobs:
         uses: actions/checkout@v3
         with:
           path: source
+          submodules: "true"
       - name: initial cabal.project for sdist
         run: |
           touch cabal.project