diff --git a/.readthedocs.yaml b/.readthedocs.yaml
index 32b65d9..6bd7a40 100644
--- a/.readthedocs.yaml
+++ b/.readthedocs.yaml
@@ -11,6 +11,10 @@ build:
   tools:
     python: "3.8"
 
+build:
+  apt_packages:
+    - graphviz
+
 # Build documentation in the "docs/" directory with Sphinx
 sphinx:
   configuration: doc/conf.py
@@ -21,4 +25,4 @@ sphinx:
 # See https://docs.readthedocs.io/en/stable/guides/reproducible-builds.html
 python:
   install:
-    - requirements: doc/requirements.txt
\ No newline at end of file
+    - requirements: doc/requirements.txt