diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 6a7f4629..6d5caf95 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -25,6 +25,8 @@ jobs:
     steps:
       - name: Checkout code
         uses: actions/checkout@v2
+        with:
+          submodules: recursive
 
       - name: Use OCaml ${{ matrix.ocaml-compiler }}
         uses: ocaml/setup-ocaml@v2