diff --git a/ci/docker/doc/Dockerfile b/ci/docker/doc/Dockerfile
index 43932ea..491257c 100644
--- a/ci/docker/doc/Dockerfile
+++ b/ci/docker/doc/Dockerfile
@@ -6,7 +6,7 @@ RUN apt update && apt install -y --no-install-recommends nodejs git ruby-rubygem
 RUN gem install asciidoctor asciidoctor-diagram
 
 # tools for diagram generation
-RUN apt install -y --no-install-recommends mscgen && apt clean
+RUN apt install -y --no-install-recommends mscgen graphviz && apt clean
 
 # tools for automatic deployment
 RUN apt install -y --no-install-recommends rsync openssh-client && apt clean