diff --git a/Dockerfile b/Dockerfile
index 5608ab8..2f8d9fc 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,6 @@
-FROM ubuntu:focal
+FROM ubuntu
+RUN sed -i -e 's/^APT/# APT/' -e 's/^DPkg/# DPkg/' \
+      /etc/apt/apt.conf.d/docker-clean
 RUN export DEBIAN_FRONTEND=noninteractive; \
 	apt update; \
 	apt install -y pandoc texlive-full