diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index f6f248f..d664561 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -20,7 +20,7 @@ Any of the following is greatly appreciated:
 As an effort to keep the codebase consistent, we encourage the use of [Rubocop](https://github.com/bbatsov/rubocop).
 This tool helps us abstract most of the decisions we have to make when coding.
 
-To check your code, simply type `rubocop` in the shell. The resulting output are all the offenses currently present in the code.
+To check your code, simply type `bundle exec rubocop` in the shell. The resulting output are all the offenses currently present in the code.
 
 It is highly recommended that you integrate a linter with your editor.
 This way you receive real time feedback about your code. Most editors have some kind of plugin for that.
diff --git a/rack-attack.gemspec b/rack-attack.gemspec
index 85aa1c6..f63c35c 100644
--- a/rack-attack.gemspec
+++ b/rack-attack.gemspec
@@ -38,6 +38,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'rack-test'
   s.add_development_dependency 'rake'
   s.add_development_dependency 'redis-activesupport'
+  s.add_development_dependency "rubocop", "0.55.0"
   s.add_development_dependency "timecop"
 
   # Need to explicitly depend on guard because guard-minitest doesn't declare