diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index a1774a82..b5d98cdb 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -23,6 +23,8 @@ jobs:
 
       - name: Setup mdBook
         uses: peaceiris/actions-mdbook@v1
+        with:
+          mdbook-version: '0.4.40'
 
       - name: Install node
         uses: actions/setup-node@v3