diff --git a/sphinx/Dockerfile b/sphinx/Dockerfile
index 036caa6..3187e3f 100644
--- a/sphinx/Dockerfile
+++ b/sphinx/Dockerfile
@@ -1,20 +1,21 @@
 ARG REGISTRY=swh-jenkins
 FROM $REGISTRY/base
 
 USER root
 RUN DEBIAN_FRONTEND=noninteractive apt-get update && \
   apt-get install -y --no-install-recommends \
     python3-sphinx \
     sphinx-rtd-theme-common \
     graphviz \
     postgresql-autodoc \
     python3-sphinxcontrib.httpdomain \
     python3-recommonmark \
     libffi-dev \
     inkscape \
     dia \
+    plantuml \
     myrepos \
     make && \
   rm -rf /var/lib/apt/lists/*
 
 USER jenkins