diff --git a/.readthedocs.yml b/.readthedocs.yml
index 2e7fd0663..4e7f5f9f3 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -4,6 +4,8 @@ build:
   os: ubuntu-22.04
   tools:
     python: "3"
+  apt_packages:
+    - graphviz
 
 formats:
   - pdf