diff --git a/.github/workflows/build_book.yaml b/.github/workflows/build_book.yaml
index fec6049..eb6fbbc 100644
--- a/.github/workflows/build_book.yaml
+++ b/.github/workflows/build_book.yaml
@@ -59,8 +59,8 @@ jobs:
         uses: actions/cache@v2
         with:
           path: _bookdown_files
-          key: bookdown-${{ hashFiles('**/*Rmd') }}
-          restore-keys: bookdown-
+          key: bookdown-1-${{ hashFiles('**/*Rmd') }}
+          restore-keys: bookdown-1-
 
       - name: Build site
         run: Rscript -e 'bookdown::render_book("index.Rmd", quiet = TRUE)'