diff --git a/.rubocop.yml b/.rubocop.yml
index e2ed9fb..7efa2c6 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -6,7 +6,7 @@ Rails:
   Enabled: true
 
 AllCops:
-  TargetRubyVersion: 2.5
+  TargetRubyVersion: 2.6
   TargetRailsVersion: 5.2
   NewCops: enable
 
diff --git a/init.rb b/init.rb
index 38f0fe0..2f8f925 100644
--- a/init.rb
+++ b/init.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-raise "\n\033[31mredmine_messenger requires ruby 2.5 or newer. Please update your ruby version.\033[0m" if RUBY_VERSION < '2.5'
+raise "\n\033[31mredmine_messenger requires ruby 2.6 or newer. Please update your ruby version.\033[0m" if RUBY_VERSION < '2.6'
 
 Redmine::Plugin.register :redmine_messenger do
   name 'Redmine Messenger'