diff --git a/sphinx/Dockerfile b/sphinx/Dockerfile
--- a/sphinx/Dockerfile
+++ b/sphinx/Dockerfile
@@ -4,12 +4,9 @@
 USER root
 RUN DEBIAN_FRONTEND=noninteractive apt-get update && \
   apt-get install -y --no-install-recommends \
-    python3-sphinx \
-    sphinx-rtd-theme-common \
+    tox \
     graphviz \
     postgresql-autodoc \
-    python3-sphinxcontrib.httpdomain \
-    python3-recommonmark \
     libffi-dev \
     inkscape \
     dia \