diff --git a/.github/workflows/guide.yml b/.github/workflows/guide.yml
index ff1e1513..c62d2c4e 100644
--- a/.github/workflows/guide.yml
+++ b/.github/workflows/guide.yml
@@ -21,7 +21,7 @@ jobs:
       - name: Setup mdBook
         uses: peaceiris/actions-mdbook@v1
         with:
-          mdbook-version: '0.4.9'
+          mdbook-version: '0.4.7'
 
       - name: Prepare tag
         id: prepare_tag
diff --git a/guide/book.toml b/guide/book.toml
index 3404e734..d34d2314 100644
--- a/guide/book.toml
+++ b/guide/book.toml
@@ -4,4 +4,4 @@ description = "PyO3 user guide"
 author = "PyO3 Project and Contributors"
 
 [preprocessor.pyo3_version]
-command = "python guide/pyo3_version.py"
+command = "python3 guide/pyo3_version.py"