diff --git a/docker/Dockerfile b/docker/Dockerfile
index 73501a9b9d..f73c4b34f0 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -1,4 +1,4 @@
-FROM bitwalker/alpine-elixir-phoenix
+FROM bitwalker/alpine-elixir-phoenix:1.9.0
 
 RUN apk --no-cache --update add alpine-sdk gmp-dev automake libtool inotify-tools autoconf python