diff --git a/.github/workflows/documentation.yml b/.github/workflows/documentation.yml
index dc3affc..977b448 100644
--- a/.github/workflows/documentation.yml
+++ b/.github/workflows/documentation.yml
@@ -20,7 +20,7 @@ jobs:
         run: |
           pip install --upgrade pip
           pip install -r requirements.txt
-          pip install sphinx furo sphinx-changelog 
+          pip install sphinx furo graphviz sphinx-changelog 
       - name: Sphinx build
         run: |
           sphinx-build docs/source _build