.travis.yml

 language: ruby
 sudo: false
 rvm:
-  - 2.2.8
-  - 2.3.5
-  - 2.4.2
-  - jruby-9.1.13.0
+  - 2.2.9
+  - 2.3.6
+  - 2.4.3
+  - 2.5.0
+  - jruby-9.1.15.0
   - rbx-2
 matrix:
   allow_failures:

Gemfile

@@ -8,8 +8,14 @@ gem "rake"
 # installed on Travis CI.
 group :development do
-  # NOTE: version should match HoundCi RuboCop version
-  gem "rubocop", require: false
+  # Force rubocop local runs to match HoundCI rubocop version
+  # (https://github.com/houndci/linters/blob/master/Gemfile.lock).
+  #
+  # This needs to be manually updated until there's a resolution
+  # on HoundCI's side.
+  #
+  # See https://github.com/houndci/hound/issues/1250
+  gem "rubocop", "0.51.0", require: false
   gem "guard-rubocop", require: false

README.md

 # Guard
-**IMPORTANT: [Ruby 2.1 is officially outdated and unsupported!](https://www.ruby-lang.org/en/news/2016/03/30/ruby-2-1-9-released/) Please upgrade to Ruby >=2.3 or >=2.2.8 before installing Guard! To install for older versions, update Bundler at least 1.12: `gem update bundler` and Bundler should correctly resolve to earlier gems for your given Ruby version.**
+**IMPORTANT: [Ruby 2.1 is officially outdated and unsupported!](https://www.ruby-lang.org/en/news/2016/03/30/ruby-2-1-9-released/) Please upgrade to Ruby >=2.3 or >=2.2.9 before installing Guard! To install for older versions, update Bundler at least 1.12: `gem update bundler` and Bundler should correctly resolve to earlier gems for your given Ruby version.**
 :exclamation: Guard is currently accepting more maintainers. Please [read this](https://github.com/guard/guard/wiki/Maintainers) if you're interested in joining the team.
@@ -32,7 +32,7 @@ Before you file an issue, make sure you have read the _[known issues](#issues)_
 * File system changes handled by our awesome [Listen](https://github.com/guard/listen) gem.
 * Support for visual system notifications.
 * Huge eco-system with [more than 220](https://rubygems.org/search?query=guard-) Guard plugins.
-* Tested against Ruby 2.2.8, 2.3.5, 2.4.2, JRuby & Rubinius.
+* Tested against Ruby 2.2.9, 2.3.6, 2.4.3, 2.5.0, JRuby & Rubinius.
 ## Screencast