diff --git a/.readthedocs.yaml b/.readthedocs.yaml
index 643b40b..426a817 100644
--- a/.readthedocs.yaml
+++ b/.readthedocs.yaml
@@ -4,6 +4,8 @@ build:
   os: ubuntu-22.04
   tools:
     python: "3.11"
+  apt_packages:
+    - graphviz
 
 sphinx:
   configuration: docs/source/conf.py