diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index b69eff6..3d09bd5 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -13,5 +13,7 @@ jobs:
         uses: actions/setup-python@v6
         with:
           python-version-file: ".python-version"
+      - name: Install graphviz and Java
+        run: sudo apt-get --yes install graphviz openjdk-21-jre
       - name: Build docs
         run: uv run sphinx-build -b html . _build/html
\ No newline at end of file
diff --git a/.github/workflows/gh_pages.yml b/.github/workflows/gh_pages.yml
index 4bf3288..0b55ac6 100644
--- a/.github/workflows/gh_pages.yml
+++ b/.github/workflows/gh_pages.yml
@@ -34,6 +34,8 @@ jobs:
         uses: actions/setup-python@v6
         with:
           python-version-file: ".python-version"
+      - name: Install graphviz and Java
+        run: sudo apt-get --yes install graphviz openjdk-21-jre
       - name: Build docs
         run: uv run sphinx-build -b html . _build/html
       - name: Upload artifact