diff --git a/.github/workflows/documentation.yaml b/.github/workflows/documentation.yaml
index 5570bb6..8a9b0e5 100644
--- a/.github/workflows/documentation.yaml
+++ b/.github/workflows/documentation.yaml
@@ -12,10 +12,10 @@ jobs:
     steps:
     - uses: actions/checkout@v2
 
-    - name: Install Doxygen
+    - name: Install Doxygen/Graphviz
       run: |
         sudo apt-get update
-        sudo apt-get install doxygen
+        sudo apt-get install doxygen graphviz
 
     - name: Build HTML documentation
       run: |