diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 4451b08..8a54abc 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -9,6 +9,8 @@ jobs:
     steps:
       - name: Checkout pdlib
         uses: actions/checkout@v3
+        with:
+          submodules: true
       - name: Setup PHP
         uses: shivammathur/setup-php@v2
         with: