diff --git a/actionpack/lib/action_controller/metal/params_wrapper.rb b/actionpack/lib/action_controller/metal/params_wrapper.rb
index 7fc898f034..a08f50143f 100644
--- a/actionpack/lib/action_controller/metal/params_wrapper.rb
+++ b/actionpack/lib/action_controller/metal/params_wrapper.rb
@@ -73,7 +73,7 @@ module ActionController
 
     require "mutex_m"
 
-    class Options < Struct.new(:name, :format, :include, :exclude, :klass, :model) # :nodoc:
+    Options = Struct.new(:name, :format, :include, :exclude, :klass, :model) do # :nodoc:
       include Mutex_m
 
       def self.from_hash(hash)
diff --git a/actionpack/lib/action_dispatch/journey/visitors.rb b/actionpack/lib/action_dispatch/journey/visitors.rb
index cda859cba4..1c50192867 100644
--- a/actionpack/lib/action_dispatch/journey/visitors.rb
+++ b/actionpack/lib/action_dispatch/journey/visitors.rb
@@ -5,7 +5,7 @@ module ActionDispatch
       ESCAPE_PATH    = ->(value) { Router::Utils.escape_path(value) }
       ESCAPE_SEGMENT = ->(value) { Router::Utils.escape_segment(value) }
 
-      class Parameter < Struct.new(:name, :escaper)
+      Parameter = Struct.new(:name, :escaper) do
         def escape(value); escaper.call value; end
       end
 
diff --git a/actionpack/test/lib/controller/fake_models.rb b/actionpack/test/lib/controller/fake_models.rb
index 046b4167bb..b768553e7a 100644
--- a/actionpack/test/lib/controller/fake_models.rb
+++ b/actionpack/test/lib/controller/fake_models.rb
@@ -1,6 +1,6 @@
 require "active_model"
 
-class Customer < Struct.new(:name, :id)
+Customer = Struct.new(:name, :id) do
   extend ActiveModel::Naming
   include ActiveModel::Conversion
 
@@ -28,7 +28,7 @@ class Customer < Struct.new(:name, :id)
   end
 end
 
-class Post < Struct.new(:title, :author_name, :body, :secret, :persisted, :written_on, :cost)
+Post = Struct.new(:title, :author_name, :body, :secret, :persisted, :written_on, :cost) do
   extend ActiveModel::Naming
   include ActiveModel::Conversion
   extend ActiveModel::Translation
diff --git a/actionview/test/actionpack/controller/render_test.rb b/actionview/test/actionpack/controller/render_test.rb
index b4a757d6b8..890041914c 100644
--- a/actionview/test/actionpack/controller/render_test.rb
+++ b/actionview/test/actionpack/controller/render_test.rb
@@ -5,7 +5,7 @@ class ApplicationController < ActionController::Base
   self.view_paths = File.join(FIXTURE_LOAD_PATH, "actionpack")
 end
 
-class Customer < Struct.new(:name, :id)
+Customer = Struct.new(:name, :id) do
   extend ActiveModel::Naming
   include ActiveModel::Conversion
 
@@ -39,7 +39,7 @@ end
 
 module Quiz
   #Models
-  class Question < Struct.new(:name, :id)
+  Question = Struct.new(:name, :id) do
     extend ActiveModel::Naming
     include ActiveModel::Conversion
 
diff --git a/actionview/test/activerecord/render_partial_with_record_identification_test.rb b/actionview/test/activerecord/render_partial_with_record_identification_test.rb
index 55886da30f..60c3ab3045 100644
--- a/actionview/test/activerecord/render_partial_with_record_identification_test.rb
+++ b/actionview/test/activerecord/render_partial_with_record_identification_test.rb
@@ -87,7 +87,7 @@ class RenderPartialWithRecordIdentificationTest < ActiveRecordTestCase
   end
 end
 
-class Game < Struct.new(:name, :id)
+Game = Struct.new(:name, :id) do
   extend ActiveModel::Naming
   include ActiveModel::Conversion
   def to_param
diff --git a/actionview/test/lib/controller/fake_models.rb b/actionview/test/lib/controller/fake_models.rb
index ddc915895d..8db52ccbe1 100644
--- a/actionview/test/lib/controller/fake_models.rb
+++ b/actionview/test/lib/controller/fake_models.rb
@@ -1,6 +1,6 @@
 require "active_model"
 
-class Customer < Struct.new(:name, :id)
+Customer = Struct.new(:name, :id) do
   extend ActiveModel::Naming
   include ActiveModel::Conversion
 
@@ -31,7 +31,7 @@ end
 class GoodCustomer < Customer
 end
 
-class Post < Struct.new(:title, :author_name, :body, :secret, :persisted, :written_on, :cost)
+Post = Struct.new(:title, :author_name, :body, :secret, :persisted, :written_on, :cost) do
   extend ActiveModel::Naming
   include ActiveModel::Conversion
   extend ActiveModel::Translation
@@ -163,7 +163,7 @@ module Blog
     true
   end
 
-  class Post < Struct.new(:title, :id)
+  Post = Struct.new(:title, :id) do
     extend ActiveModel::Naming
     include ActiveModel::Conversion
 
@@ -183,8 +183,7 @@ class ArelLike
   end
 end
 
-class Car < Struct.new(:color)
-end
+Car = Struct.new(:color)
 
 class Plane
   attr_reader :to_key
diff --git a/actionview/test/template/active_model_helper_test.rb b/actionview/test/template/active_model_helper_test.rb
index 8b8f686f96..6b63aa25a5 100644
--- a/actionview/test/template/active_model_helper_test.rb
+++ b/actionview/test/template/active_model_helper_test.rb
@@ -4,7 +4,7 @@ class ActiveModelHelperTest < ActionView::TestCase
   tests ActionView::Helpers::ActiveModelHelper
 
   silence_warnings do
-    class Post < Struct.new(:author_name, :body, :updated_at)
+    Post = Struct.new(:author_name, :body, :updated_at) do
       include ActiveModel::Conversion
       include ActiveModel::Validations
 
diff --git a/actionview/test/template/atom_feed_helper_test.rb b/actionview/test/template/atom_feed_helper_test.rb
index e9a923dd72..1245a1a966 100644
--- a/actionview/test/template/atom_feed_helper_test.rb
+++ b/actionview/test/template/atom_feed_helper_test.rb
@@ -1,6 +1,6 @@
 require "abstract_unit"
 
-class Scroll < Struct.new(:id, :to_param, :title, :body, :updated_at, :created_at)
+Scroll = Struct.new(:id, :to_param, :title, :body, :updated_at, :created_at) do
   extend ActiveModel::Naming
   include ActiveModel::Conversion
 
diff --git a/actionview/test/template/form_collections_helper_test.rb b/actionview/test/template/form_collections_helper_test.rb
index 3774dcf872..6160524eb3 100644
--- a/actionview/test/template/form_collections_helper_test.rb
+++ b/actionview/test/template/form_collections_helper_test.rb
@@ -1,7 +1,6 @@
 require "abstract_unit"
 
-class Category < Struct.new(:id, :name)
-end
+Category = Struct.new(:id, :name)
 
 class FormCollectionsHelperTest < ActionView::TestCase
   def assert_no_select(selector, value = nil)
diff --git a/activerecord/lib/active_record/associations/join_dependency.rb b/activerecord/lib/active_record/associations/join_dependency.rb
index 4cd1e64c3d..a79eb03acc 100644
--- a/activerecord/lib/active_record/associations/join_dependency.rb
+++ b/activerecord/lib/active_record/associations/join_dependency.rb
@@ -32,7 +32,7 @@ module ActiveRecord
           @alias_cache[node][column]
         end
 
-        class Table < Struct.new(:node, :columns) # :nodoc:
+        Table = Struct.new(:node, :columns) do # :nodoc:
           def table
             Arel::Nodes::TableAlias.new node.table, node.aliased_table_name
           end
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
index 9b324c090b..b518ef760b 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
@@ -3,29 +3,25 @@ module ActiveRecord
     # Abstract representation of an index definition on a table. Instances of
     # this type are typically created and returned by methods in database
     # adapters. e.g. ActiveRecord::ConnectionAdapters::AbstractMysqlAdapter#indexes
-    class IndexDefinition < Struct.new(:table, :name, :unique, :columns, :lengths, :orders, :where, :type, :using, :comment) #:nodoc:
-    end
+    IndexDefinition = Struct.new(:table, :name, :unique, :columns, :lengths, :orders, :where, :type, :using, :comment) #:nodoc:
 
     # Abstract representation of a column definition. Instances of this type
     # are typically created by methods in TableDefinition, and added to the
     # +columns+ attribute of said TableDefinition object, in order to be used
     # for generating a number of table creation or table changing SQL statements.
-    class ColumnDefinition < Struct.new(:name, :type, :limit, :precision, :scale, :default, :null, :first, :after, :auto_increment, :primary_key, :collation, :sql_type, :comment) #:nodoc:
+    ColumnDefinition = Struct.new(:name, :type, :limit, :precision, :scale, :default, :null, :first, :after, :auto_increment, :primary_key, :collation, :sql_type, :comment) do #:nodoc:
       def primary_key?
         primary_key || type.to_sym == :primary_key
       end
     end
 
-    class AddColumnDefinition < Struct.new(:column) # :nodoc:
-    end
+    AddColumnDefinition = Struct.new(:column) # :nodoc:
 
-    class ChangeColumnDefinition < Struct.new(:column, :name) #:nodoc:
-    end
+    ChangeColumnDefinition = Struct.new(:column, :name) #:nodoc:
 
-    class PrimaryKeyDefinition < Struct.new(:name) # :nodoc:
-    end
+    PrimaryKeyDefinition = Struct.new(:name) # :nodoc:
 
-    class ForeignKeyDefinition < Struct.new(:from_table, :to_table, :options) #:nodoc:
+    ForeignKeyDefinition = Struct.new(:from_table, :to_table, :options) do #:nodoc:
       def name
         options[:name]
       end
diff --git a/activerecord/lib/active_record/migration.rb b/activerecord/lib/active_record/migration.rb
index 6e5f5fa2a7..31c2397bc9 100644
--- a/activerecord/lib/active_record/migration.rb
+++ b/activerecord/lib/active_record/migration.rb
@@ -692,7 +692,7 @@ module ActiveRecord
       connection.respond_to?(:reverting) && connection.reverting
     end
 
-    class ReversibleBlockHelper < Struct.new(:reverting) # :nodoc:
+    ReversibleBlockHelper = Struct.new(:reverting) do # :nodoc:
       def up
         yield unless reverting
       end
@@ -938,7 +938,7 @@ module ActiveRecord
 
   # MigrationProxy is used to defer loading of the actual migration classes
   # until they are needed
-  class MigrationProxy < Struct.new(:name, :version, :filename, :scope)
+  MigrationProxy = Struct.new(:name, :version, :filename, :scope) do
     def initialize(name, version, filename, scope)
       super
       @migration = nil
diff --git a/activerecord/test/cases/attribute_methods/read_test.rb b/activerecord/test/cases/attribute_methods/read_test.rb
index 978dd93fa4..1fc63a49d4 100644
--- a/activerecord/test/cases/attribute_methods/read_test.rb
+++ b/activerecord/test/cases/attribute_methods/read_test.rb
@@ -3,7 +3,7 @@ require "cases/helper"
 module ActiveRecord
   module AttributeMethods
     class ReadTest < ActiveRecord::TestCase
-      class FakeColumn < Struct.new(:name)
+      FakeColumn = Struct.new(:name) do
         def type; :integer; end
       end
 
diff --git a/activerecord/test/cases/relation/mutation_test.rb b/activerecord/test/cases/relation/mutation_test.rb
index de15eb9187..4f92f71a09 100644
--- a/activerecord/test/cases/relation/mutation_test.rb
+++ b/activerecord/test/cases/relation/mutation_test.rb
@@ -3,7 +3,7 @@ require "models/post"
 
 module ActiveRecord
   class RelationMutationTest < ActiveRecord::TestCase
-    class FakeKlass < Struct.new(:table_name, :name)
+    FakeKlass = Struct.new(:table_name, :name) do
       extend ActiveRecord::Delegation::DelegateCache
       inherited self
 
diff --git a/activerecord/test/cases/relation_test.rb b/activerecord/test/cases/relation_test.rb
index d5af0cc9a5..1241bb54a4 100644
--- a/activerecord/test/cases/relation_test.rb
+++ b/activerecord/test/cases/relation_test.rb
@@ -8,7 +8,7 @@ module ActiveRecord
   class RelationTest < ActiveRecord::TestCase
     fixtures :posts, :comments, :authors
 
-    class FakeKlass < Struct.new(:table_name, :name)
+    FakeKlass = Struct.new(:table_name, :name) do
       extend ActiveRecord::Delegation::DelegateCache
 
       inherited self
diff --git a/activesupport/lib/active_support/execution_wrapper.rb b/activesupport/lib/active_support/execution_wrapper.rb
index 3384d12d5b..ca88e7876b 100644
--- a/activesupport/lib/active_support/execution_wrapper.rb
+++ b/activesupport/lib/active_support/execution_wrapper.rb
@@ -19,14 +19,14 @@ module ActiveSupport
       set_callback(:complete, *args, &block)
     end
 
-    class RunHook < Struct.new(:hook) # :nodoc:
+    RunHook = Struct.new(:hook) do # :nodoc:
       def before(target)
         hook_state = target.send(:hook_state)
         hook_state[hook] = hook.run
       end
     end
 
-    class CompleteHook < Struct.new(:hook) # :nodoc:
+    CompleteHook = Struct.new(:hook) do # :nodoc:
       def before(target)
         hook_state = target.send(:hook_state)
         if hook_state.key?(hook)
diff --git a/activesupport/test/core_ext/module_test.rb b/activesupport/test/core_ext/module_test.rb
index a4515d1956..f89cb338ba 100644
--- a/activesupport/test/core_ext/module_test.rb
+++ b/activesupport/test/core_ext/module_test.rb
@@ -24,7 +24,7 @@ Somewhere = Struct.new(:street, :city) do
   attr_accessor :name
 end
 
-class Someone < Struct.new(:name, :place)
+Someone = Struct.new(:name, :place) do
   delegate :street, :city, :to_f, to: :place
   delegate :name=, to: :place, prefix: true
   delegate :upcase, to: "place.city"
diff --git a/activesupport/test/json/encoding_test_cases.rb b/activesupport/test/json/encoding_test_cases.rb
index 8eac246937..b2f0cf3048 100644
--- a/activesupport/test/json/encoding_test_cases.rb
+++ b/activesupport/test/json/encoding_test_cases.rb
@@ -23,7 +23,7 @@ module JSONTest
     end
   end
 
-  class MyStruct < Struct.new(:name, :value)
+  MyStruct = Struct.new(:name, :value) do
     def initialize(*)
       @unused = "unused instance variable"
       super
diff --git a/railties/lib/rails/generators/app_base.rb b/railties/lib/rails/generators/app_base.rb
index ea88afe9f4..2297a31b6d 100644
--- a/railties/lib/rails/generators/app_base.rb
+++ b/railties/lib/rails/generators/app_base.rb
@@ -209,7 +209,7 @@ module Rails
         !options[:skip_active_record] && options[:database] == "sqlite3"
       end
 
-      class GemfileEntry < Struct.new(:name, :version, :comment, :options, :commented_out)
+      GemfileEntry = Struct.new(:name, :version, :comment, :options, :commented_out) do
         def initialize(name, version, comment, options = {}, commented_out = false)
           super
         end
diff --git a/railties/lib/rails/source_annotation_extractor.rb b/railties/lib/rails/source_annotation_extractor.rb
index 3a48c4c496..e9088c44ce 100644
--- a/railties/lib/rails/source_annotation_extractor.rb
+++ b/railties/lib/rails/source_annotation_extractor.rb
@@ -13,7 +13,7 @@
 # start with the tag optionally followed by a colon. Everything up to the end
 # of the line (or closing ERB comment tag) is considered to be their text.
 class SourceAnnotationExtractor
-  class Annotation < Struct.new(:line, :tag, :text)
+  Annotation = Struct.new(:line, :tag, :text) do
     def self.directories
       @@directories ||= %w(app config db lib test) + (ENV["SOURCE_ANNOTATION_DIRECTORIES"] || "").split(",")
     end
diff --git a/railties/test/rack_logger_test.rb b/railties/test/rack_logger_test.rb
index 7dd91a2465..33b4bc6a3a 100644
--- a/railties/test/rack_logger_test.rb
+++ b/railties/test/rack_logger_test.rb
@@ -20,7 +20,7 @@ module Rails
         def development?; false; end
       end
 
-      class Subscriber < Struct.new(:starts, :finishes)
+      Subscriber = Struct.new(:starts, :finishes) do
         def initialize(starts = [], finishes = [])
           super
         end