diff --git a/.readthedocs.yml b/.readthedocs.yml
index ef3c4b0c..30684052 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -8,6 +8,8 @@ build:
   os: ubuntu-22.04
   tools:
     python: "3.11"
+  apt_packages:
+  - graphviz
 
 python:
   install:
diff --git a/doc/requirements.txt b/doc/requirements.txt
index de3ed4e8..3e760c81 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -7,7 +7,6 @@ sphinx
 sphinx_book_theme
 sphinxcontrib-bibtex
 myst-parser  # recommark is deprecated, https://stackoverflow.com/a/71660856/13573820
-graphviz
 
 pypsa
 powerplantmatching>=0.5.5