diff --git a/Gemfile b/Gemfile
index a972ebfaf64..8674cb2a521 100644
--- a/Gemfile
+++ b/Gemfile
@@ -56,6 +56,9 @@ group :rubocop do
   gem "rubocop-performance", require: false
   gem "rubocop-rails", require: false
   gem "rubocop-md", require: false
+
+  # This gem is used in Railties tests so it must be a development dependency.
+  gem "rubocop-rails-omakase", require: false
 end
 
 group :mdl do
diff --git a/Gemfile.lock b/Gemfile.lock
index 8a9cd6a8004..d18371595b0 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -469,6 +469,11 @@ GEM
       activesupport (>= 4.2.0)
       rack (>= 1.1)
       rubocop (>= 1.33.0, < 2.0)
+    rubocop-rails-omakase (1.0.0)
+      rubocop
+      rubocop-minitest
+      rubocop-performance
+      rubocop-rails
     ruby-progressbar (1.13.0)
     ruby-vips (2.1.4)
       ffi (~> 1.12)
@@ -632,6 +637,7 @@ DEPENDENCIES
   rubocop-packaging
   rubocop-performance
   rubocop-rails
+  rubocop-rails-omakase
   rubyzip (~> 2.0)
   sdoc!
   selenium-webdriver (>= 4.11.0)