diff --git a/.readthedocs.yml b/.readthedocs.yml
index ed57d26..48949cd 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -1,6 +1,7 @@
 version: 2
 formats:
   - epub
+  - pdf
 build:
   os: ubuntu-22.04
   tools:
@@ -11,6 +12,7 @@ build:
     - gcc
     - libcups2-dev
     - python3-dev
+    - xindy
 sphinx:
   configuration: doc/conf.py
 submodules:
diff --git a/doc/conf.py b/doc/conf.py
index a2079fe..5fc6101 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -225,7 +225,7 @@ latex_elements = {
     #'preamble': '',
 }
 
-# latex_engine = "xelatex"
+latex_engine = "xelatex"
 
 # Grouping the document tree into LaTeX files. List of tuples
 # (source start file, target name, title,