diff --git a/.github/workflows/build-docs.yml b/.github/workflows/build-docs.yml
index 595473e5a..8ed07abd0 100644
--- a/.github/workflows/build-docs.yml
+++ b/.github/workflows/build-docs.yml
@@ -13,6 +13,7 @@ jobs:
         with:
           fetch-depth: 0
           ref: main
+          submodules: true
       - name: Set up Python
         uses: actions/setup-python@v1
         with: