diff --git a/.github/workflows/deploy_mkdocs.yml b/.github/workflows/deploy_mkdocs.yml
index a8281a1de0..4d6fd9104e 100644
--- a/.github/workflows/deploy_mkdocs.yml
+++ b/.github/workflows/deploy_mkdocs.yml
@@ -39,10 +39,10 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - name: Checkout ${{ inputs.branch_name }}
+      - name: Checkout ${{ inputs.branch_name || 'main' }}
         uses: actions/checkout@v4
         with:
-          ref: ${{ inputs.branch_name }}
+          ref: ${{ inputs.branch_name || 'main' }}
           fetch-depth: 0
           submodules: true