diff --git a/.rubocop.yml b/.rubocop.yml
index 9ab6f6b3..15562dab 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -3,6 +3,7 @@ inherit_from: .rubocop_todo.yml
 
 # Apply rule to all cops
 AllCops:
+  TargetRubyVersion: 2.4
   Include:
     - '**/Rakefile'
     - '**/config.ru'
diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index 5486bd0c..a50e6fa3 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -710,3 +710,12 @@ Style/TrailingCommaInLiteral:
     - 'Guardfile'
     - 'db/migrate/20140701123203_add_events_per_week_to_conference.rb'
     - 'spec/models/conference_spec.rb'
+
+
+# for ruby 3.0
+Style/FrozenStringLiteralComment:
+  Enabled: false
+Style/NumericPredicate:
+  Enabled: false
+Style/SafeNavigation:
+  Enabled: false