diff --git a/.rubocop.yml b/.rubocop.yml
index c474484..0fbff00 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -6,8 +6,9 @@ Rails:
   Enabled: true
 
 AllCops:
-  TargetRubyVersion: 2.3
+  TargetRubyVersion: 2.4
   TargetRailsVersion: 5.2
+  NewCops: enable
 
 Metrics:
   Enabled: false
@@ -45,17 +46,8 @@ Style/Documentation:
 Style/ExpandPathArguments:
   Enabled: false
 
-Style/HashEachMethods:
-  Enabled: true
-
 Style/HashTransformKeys:
   Enabled: false
 
 Style/HashTransformValues:
   Enabled: false
-
-Lint/RaiseException:
-  Enabled: true
-
-Lint/StructNewOverride:
-  Enabled: true
diff --git a/CHANGELOG.md b/CHANGELOG.md
index a3f6c78..8ca48f3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ Changelog
 - Redundant status and priority in messages #56
 - Show attachments for new issues
 - Show indicator for private comment on issue
+- Ruby 2.4 or higher is required
 
 1.0.5
 -----
diff --git a/init.rb b/init.rb
index 19eac27..41efda4 100644
--- a/init.rb
+++ b/init.rb
@@ -1,4 +1,4 @@
-raise "\n\033[31mredmine_messenger requires ruby 2.3 or newer. Please update your ruby version.\033[0m" if RUBY_VERSION < '2.3'
+raise "\n\033[31mredmine_messenger requires ruby 2.4 or newer. Please update your ruby version.\033[0m" if RUBY_VERSION < '2.4'
 
 Redmine::Plugin.register :redmine_messenger do
   name 'Redmine Messenger'