diff --git a/.github/workflows/build_book.yaml b/.github/workflows/build_book.yaml
index b45cb24..f6fc20c 100644
--- a/.github/workflows/build_book.yaml
+++ b/.github/workflows/build_book.yaml
@@ -42,6 +42,10 @@ jobs:
         run: |
           Rscript -e "install.packages('bookdown')"
 
+      - name: Install cowplot
+        run: |
+          Rscript -e "install.packages('cowplot')"
+
       - name: Render book
         run: |
           Rscript -e "bookdown::render_book()"