diff --git a/Dockerfile b/Dockerfile
index df8e229..885e510 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,8 +1,8 @@
 FROM heroku/heroku:18-build
 
 # Which versions?
-ENV RUBY_MAJOR_VERSION 2.7.0
-ENV RUBY_VERSION 2.7.0
+ENV RUBY_MAJOR_VERSION 2.5.7
+ENV RUBY_VERSION 2.5.7
 # https://devcenter.heroku.com/articles/ruby-support#libraries
 ENV BUNDLER_VERSION 2.0.2
 ENV NODE_VERSION 12.14.1
diff --git a/README.md b/README.md
index faa5204..8203d4b 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,7 @@ Usage: `FROM nerdsandcompany/docker-heroku-rails`
 # Specifications
 
 * Heroku 18
-* Ruby 2.7.0
+* Ruby 2.5.7
 * Bundler 2.0.2
 * Node 12.14.1
 * Yarn 1.21.1