diff --git a/Dockerfile b/Dockerfile
index a95a058986485a90910852ae1c379c7d9a3f6b0e..15efb6cbb8fb56f702eee3f96e9a79bd36fe9242 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-ubuntu:xenial
+FROM ubuntu:xenial
 MAINTAINER Bas Nijholt <bas@nijho.lt>
 
 ENV LANG=C.UTF-8 LC_ALL=C.UTF-8