diff --git a/.readthedocs.yaml b/.readthedocs.yaml
index 4fa27769..9b618d15 100644
--- a/.readthedocs.yaml
+++ b/.readthedocs.yaml
@@ -6,6 +6,8 @@ version: 2
 
 build:
   os: ubuntu-20.04
+  apt_packages:
+    - graphviz
   tools:
     python: "3.10"