diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 3d50e05..1540f69 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -21,7 +21,9 @@ jobs:
             bin: g++
     steps:
       - name: checkout-scm
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
+        with:
+          submodules: recursive
       - name: setup
         run: sudo apt install ${{ matrix.compiler.package }} make
       - name: test