diff --git a/gcp-ts-k8s-ruby-on-rails-postgresql/app/Dockerfile b/gcp-ts-k8s-ruby-on-rails-postgresql/app/Dockerfile
index 185a7c25e..c1c3b4d45 100644
--- a/gcp-ts-k8s-ruby-on-rails-postgresql/app/Dockerfile
+++ b/gcp-ts-k8s-ruby-on-rails-postgresql/app/Dockerfile
@@ -1,4 +1,4 @@
-FROM ruby:2.5
+FROM ruby:2.5.1
 RUN apt-get update -qq && apt-get install -y build-essential libpq-dev nodejs
 RUN mkdir /myapp
 WORKDIR /myapp