diff --git a/Dockerfile b/Dockerfile
index f721f7d..84059e4 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM ubuntu:focal
+FROM ubuntu:20.04
 
 ENV DEBIAN_FRONTEND=noninteractive LC_ALL=en_US.UTF-8 LANG=en_US.UTF-8 LAIN_IGNORE_LINT="true" PS1="lain# "