diff --git a/.rubocop.yml b/.rubocop.yml
index a5575bf5e..881bd428e 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -376,6 +376,9 @@ Style/BlockDelimiters:
 Style/ClassCheck:
   Enabled: true
 
+Style/ClassVars:
+  Enabled: true
+
 Style/Not:
   Enabled: true
 
diff --git a/app/models/concerns/measurable.rb b/app/models/concerns/measurable.rb
index affb113c2..84ed5055d 100644
--- a/app/models/concerns/measurable.rb
+++ b/app/models/concerns/measurable.rb
@@ -3,11 +3,11 @@ module Measurable
 
   class_methods do
     def title_max_length
-      @@title_max_length ||= (columns.find { |c| c.name == "title" }.limit rescue nil) || 80
+      @title_max_length ||= (columns.find { |c| c.name == "title" }.limit rescue nil) || 80
     end
 
     def responsible_name_max_length
-      @@responsible_name_max_length ||= (columns.find { |c| c.name == "responsible_name" }.limit rescue nil) || 60
+      @responsible_name_max_length ||= (columns.find { |c| c.name == "responsible_name" }.limit rescue nil) || 60
     end
 
     def question_max_length
diff --git a/app/models/organization.rb b/app/models/organization.rb
index 32d545249..abda49873 100644
--- a/app/models/organization.rb
+++ b/app/models/organization.rb
@@ -42,11 +42,11 @@ class Organization < ApplicationRecord
   end
 
   def self.name_max_length
-    @@name_max_length ||= columns.find { |c| c.name == "name" }.limit || 60
+    @name_max_length ||= columns.find { |c| c.name == "name" }.limit || 60
   end
 
   def self.responsible_name_max_length
-    @@responsible_name_max_length ||= columns.find { |c| c.name == "responsible_name" }.limit || 60
+    @responsible_name_max_length ||= columns.find { |c| c.name == "responsible_name" }.limit || 60
   end
 
   private
diff --git a/app/models/user.rb b/app/models/user.rb
index 43927fe39..ee618566d 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -313,7 +313,7 @@ class User < ApplicationRecord
   end
 
   def self.username_max_length
-    @@username_max_length ||= columns.find { |c| c.name == "username" }.limit || 60
+    @username_max_length ||= columns.find { |c| c.name == "username" }.limit || 60
   end
 
   def self.minimum_required_age