diff --git a/Dockerfile b/Dockerfile
index 6f00b7b..5608ab8 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM ubuntu
+FROM ubuntu:focal
 RUN export DEBIAN_FRONTEND=noninteractive; \
 	apt update; \
 	apt install -y pandoc texlive-full