diff --git a/.github/workflows/sphinx-compile-test.yml b/.github/workflows/sphinx-compile-test.yml
index ab116d7..e557b94 100644
--- a/.github/workflows/sphinx-compile-test.yml
+++ b/.github/workflows/sphinx-compile-test.yml
@@ -21,6 +21,10 @@ jobs:
       - name: Install Sphinx
         run: |
           sudo apt install python3-sphinx-rtd-theme
+      - name: Install Graphviz
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y graphviz
       - name: Setup Pages
         id: pages
         uses: actions/configure-pages@v5
diff --git a/.github/workflows/sphinx-github-pages-deploy.yml b/.github/workflows/sphinx-github-pages-deploy.yml
index 797edf5..1a32fcf 100644
--- a/.github/workflows/sphinx-github-pages-deploy.yml
+++ b/.github/workflows/sphinx-github-pages-deploy.yml
@@ -34,6 +34,10 @@ jobs:
       - name: Install Sphinx
         run: |
           sudo apt install python3-sphinx-rtd-theme
+      - name: Install Graphviz
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y graphviz
       - name: Setup Pages
         id: pages
         uses: actions/configure-pages@v5