diff --git a/dockerfile b/dockerfile
index 3f83fb9..2bd9bee 100644
--- a/dockerfile
+++ b/dockerfile
@@ -1,4 +1,4 @@
-FROM ubuntu:16.04
+FROM ubuntu:xenial-20210416
 
 RUN apt-get clean && apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y locales
 RUN locale-gen en_US.UTF-8