diff --git a/docker/dev/Dockerfile b/docker/dev/Dockerfile
index f5c9b408..375397b5 100644
--- a/docker/dev/Dockerfile
+++ b/docker/dev/Dockerfile
@@ -18,4 +18,4 @@ WORKDIR /usr/src/diagrams
 COPY . .
 
 # install python requirements.
-RUN pip install black
+RUN pip install black graphviz