diff --git a/.rubocop.yml b/.rubocop.yml
index 673f19f..5fa131f 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -4,7 +4,7 @@ Rails:
   Enabled: true
 
 AllCops:
-  TargetRubyVersion: 2.2
+  TargetRubyVersion: 2.3
   TargetRailsVersion: 5.2
 
 Metrics/AbcSize:
@@ -47,6 +47,9 @@ Performance/ChainArrayAllocation:
 Style/AutoResourceCleanup:
   Enabled: true
 
+Style/FrozenStringLiteralComment:
+  Enabled: false
+
 Style/Documentation:
   Enabled: false
 
diff --git a/.travis.yml b/.travis.yml
index 6167ffa..5a826f2 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,9 +1,9 @@
 language: ruby
 
 rvm:
+  - 2.5.3
   - 2.4.5
   - 2.3.8
-  - 2.2.10
 
 env:
   - REDMINE_VER=4.0-stable DB=postgresql
diff --git a/CHANGELOG.md b/CHANGELOG.md
index ab4f861..aea29fb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,12 @@
 Changelog
 =========
 
+1.0.5
+-----
+
+- ruby 2.3.x or newer is required
+
+
 1.0.4
 -----
 
diff --git a/README.md b/README.md
index c66fc68..6174479 100644
--- a/README.md
+++ b/README.md
@@ -57,7 +57,7 @@ Requirements
 ------------
 
 * Redmine version >= 3.0.0
-* Ruby version >= 2.2.10
+* Ruby version >= 2.3.0
 
 
 Installation
diff --git a/app/models/messenger.rb b/app/models/messenger.rb
index 578fe20..7683021 100644
--- a/app/models/messenger.rb
+++ b/app/models/messenger.rb
@@ -29,7 +29,7 @@ class Messenger
 
     username = Messenger.textfield_for_project(options[:project], :messenger_username)
     params[:username] = username if username.present?
-    params[:attachments] = [options[:attachment]] if options[:attachment] && options[:attachment].any?
+    params[:attachments] = [options[:attachment]] if options[:attachment]&.any?
 
     icon = Messenger.textfield_for_project(options[:project], :messenger_icon)
     if icon.present?
diff --git a/init.rb b/init.rb
index eb71ac6..5c215ae 100644
--- a/init.rb
+++ b/init.rb
@@ -1,3 +1,5 @@
+raise "\n\033[31mredmine_messenger requires ruby 2.3 or newer. Please update your ruby version.\033[0m" if RUBY_VERSION < '2.3'
+
 require 'redmine'
 require 'redmine_messenger'
 
@@ -7,7 +9,7 @@ Redmine::Plugin.register :redmine_messenger do
   url 'https://github.com/alphanodes/redmine_messenger'
   author_url 'https://alphanodes.com/'
   description 'Messenger integration for Slack, Discord, Rocketchat and Mattermost support'
-  version '1.0.4'
+  version '1.0.5'
 
   requires_redmine version_or_higher: '3.0.0'
 
diff --git a/lib/redmine_messenger/patches/issue_patch.rb b/lib/redmine_messenger/patches/issue_patch.rb
index 25164bb..73dca00 100644
--- a/lib/redmine_messenger/patches/issue_patch.rb
+++ b/lib/redmine_messenger/patches/issue_patch.rb
@@ -35,7 +35,7 @@ module RedmineMessenger
                                      short: true }
           end
 
-          if RedmineMessenger.setting?(:display_watchers) && watcher_users.count > 0
+          if RedmineMessenger.setting?(:display_watchers) && watcher_users.count.positive?
             attachment[:fields] << {
               title: I18n.t(:field_watcher),
               value: ERB::Util.html_escape(watcher_users.join(', ')),