diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 4565afa..a792204 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -24,6 +24,8 @@ jobs:
         os: [ubuntu-latest]
     runs-on: ${{ matrix.os }}
     steps:
+      - name: Install graphviz deps
+        run: apt-get install -y graphviz-dev
       - uses: actions/checkout@v2
       - uses: actions/setup-python@v2
         with: