diff --git a/Dockerfile-bullseye b/Dockerfile-bullseye
index 34edb86..4dde056 100644
--- a/Dockerfile-bullseye
+++ b/Dockerfile-bullseye
@@ -55,6 +55,7 @@ RUN <<EOF
   LC_ALL=C DEBIAN_FRONTEND=noninteractive apt-get update 
   LC_ALL=C DEBIAN_FRONTEND=noninteractive apt-get install -qqy --no-install-recommends \
       libusb-dev \
+      graphviz \
       python3-dev  
   LC_ALL=C apt-get autoremove -qqy && LC_ALL=C apt-get clean 
   rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* ~/.[^.] ~/.??* ~/*