diff --git a/.github/workflows/sphinx-books-tests.js.yml b/.github/workflows/sphinx-books-tests.js.yml
index 974a383b1..763bf2640 100644
--- a/.github/workflows/sphinx-books-tests.js.yml
+++ b/.github/workflows/sphinx-books-tests.js.yml
@@ -45,6 +45,7 @@ jobs:
         texlive-fonts-extra \
         latexmk \
         texlive-xetex \
+        xindy \
         fonts-lmodern \
         fonts-open-sans \
         fonts-dejavu \