diff --git a/activerecord/lib/active_record/serialization.rb b/activerecord/lib/active_record/serialization.rb
index 6b55af4205329864878ed320dbc555eb0ed20513..bd9079b596c38ecf886155187d1f53861a53e6fd 100644
--- a/activerecord/lib/active_record/serialization.rb
+++ b/activerecord/lib/active_record/serialization.rb
@@ -5,7 +5,7 @@ module Serialization
     include ActiveModel::Serializers::JSON
 
     included do
-      self.include_root_in_json = true
+      self.include_root_in_json = false
     end
 
     def serializable_hash(options = nil)
diff --git a/activerecord/test/cases/json_serialization_test.rb b/activerecord/test/cases/json_serialization_test.rb
index a86b165c7845bc5e0f83c4bcd3a93b63aedf7d8b..a2226759182f5866dc6f9120418217a06755d6a8 100644
--- a/activerecord/test/cases/json_serialization_test.rb
+++ b/activerecord/test/cases/json_serialization_test.rb
@@ -6,7 +6,21 @@
 require 'models/tag'
 require 'models/comment'
 
+module JsonSerializationHelpers
+  private
+
+  def set_include_root_in_json(value)
+    original_root_in_json = ActiveRecord::Base.include_root_in_json
+    ActiveRecord::Base.include_root_in_json = value
+    yield
+  ensure
+    ActiveRecord::Base.include_root_in_json = original_root_in_json
+  end
+end
+
 class JsonSerializationTest < ActiveRecord::TestCase
+  include JsonSerializationHelpers
+
   class NamespacedContact < Contact
     column :name, :string
   end
@@ -23,20 +37,24 @@ def setup
   end
 
   def test_should_demodulize_root_in_json
-    @contact = NamespacedContact.new :name => 'whatever'
-    json = @contact.to_json
-    assert_match %r{^\{"namespaced_contact":\{}, json
+    set_include_root_in_json(true) do
+      @contact = NamespacedContact.new name: 'whatever'
+      json = @contact.to_json
+      assert_match %r{^\{"namespaced_contact":\{}, json
+    end
   end
 
   def test_should_include_root_in_json
-    json = @contact.to_json
-
-    assert_match %r{^\{"contact":\{}, json
-    assert_match %r{"name":"Konata Izumi"}, json
-    assert_match %r{"age":16}, json
-    assert json.include?(%("created_at":#{ActiveSupport::JSON.encode(Time.utc(2006, 8, 1))}))
-    assert_match %r{"awesome":true}, json
-    assert_match %r{"preferences":\{"shows":"anime"\}}, json
+    set_include_root_in_json(true) do
+      json = @contact.to_json
+
+      assert_match %r{^\{"contact":\{}, json
+      assert_match %r{"name":"Konata Izumi"}, json
+      assert_match %r{"age":16}, json
+      assert json.include?(%("created_at":#{ActiveSupport::JSON.encode(Time.utc(2006, 8, 1))}))
+      assert_match %r{"awesome":true}, json
+      assert_match %r{"preferences":\{"shows":"anime"\}}, json
+    end
   end
 
   def test_should_encode_all_encodable_attributes
@@ -141,6 +159,8 @@ def test_serializable_hash_should_not_modify_options_in_argument
 class DatabaseConnectedJsonEncodingTest < ActiveRecord::TestCase
   fixtures :authors, :posts, :comments, :tags, :taggings
 
+  include JsonSerializationHelpers
+
   def setup
     @david = authors(:david)
     @mary = authors(:mary)
@@ -227,23 +247,21 @@ def @david.favorite_quote; "Constraints are liberating"; end
   end
 
   def test_should_allow_only_option_for_list_of_authors
-    ActiveRecord::Base.include_root_in_json = false
-    authors = [@david, @mary]
-    assert_equal %([{"name":"David"},{"name":"Mary"}]), ActiveSupport::JSON.encode(authors, :only => :name)
-  ensure
-    ActiveRecord::Base.include_root_in_json = true
+    set_include_root_in_json(false) do
+      authors = [@david, @mary]
+      assert_equal %([{"name":"David"},{"name":"Mary"}]), ActiveSupport::JSON.encode(authors, only: :name)
+    end
   end
 
   def test_should_allow_except_option_for_list_of_authors
-    ActiveRecord::Base.include_root_in_json = false
-    authors = [@david, @mary]
-    encoded = ActiveSupport::JSON.encode(authors, :except => [
-      :name, :author_address_id, :author_address_extra_id,
-      :organization_id, :owned_essay_id
-    ])
-    assert_equal %([{"id":1},{"id":2}]), encoded
-  ensure
-    ActiveRecord::Base.include_root_in_json = true
+    set_include_root_in_json(false) do
+      authors = [@david, @mary]
+      encoded = ActiveSupport::JSON.encode(authors, except: [
+        :name, :author_address_id, :author_address_extra_id,
+        :organization_id, :owned_essay_id
+      ])
+      assert_equal %([{"id":1},{"id":2}]), encoded
+    end
   end
 
   def test_should_allow_includes_for_list_of_authors
@@ -262,17 +280,21 @@ def test_should_allow_includes_for_list_of_authors
   end
 
   def test_should_allow_options_for_hash_of_authors
-    authors_hash = {
-      1 => @david,
-      2 => @mary
-    }
-    assert_equal %({"1":{"author":{"name":"David"}}}), ActiveSupport::JSON.encode(authors_hash, :only => [1, :name])
+    set_include_root_in_json(true) do
+      authors_hash = {
+        1 => @david,
+        2 => @mary
+      }
+      assert_equal %({"1":{"author":{"name":"David"}}}), ActiveSupport::JSON.encode(authors_hash, only: [1, :name])
+    end
   end
 
   def test_should_be_able_to_encode_relation
-    authors_relation = Author.where(:id => [@david.id, @mary.id])
+    set_include_root_in_json(true) do
+      authors_relation = Author.where(id: [@david.id, @mary.id])
 
-    json = ActiveSupport::JSON.encode authors_relation, :only => :name
-    assert_equal '[{"author":{"name":"David"}},{"author":{"name":"Mary"}}]', json
+      json = ActiveSupport::JSON.encode authors_relation, only: :name
+      assert_equal '[{"author":{"name":"David"}},{"author":{"name":"Mary"}}]', json
+    end
   end
 end
diff --git a/activerecord/test/cases/serialization_test.rb b/activerecord/test/cases/serialization_test.rb
index eb9cb91e320e6615d58a8cdeafac56c0e25b90aa..c46060a6460270fcf54b7192d22d9f7c15b1c9f7 100644
--- a/activerecord/test/cases/serialization_test.rb
+++ b/activerecord/test/cases/serialization_test.rb
@@ -18,6 +18,10 @@ def setup
     }
   end
 
+  def test_include_root_in_json_is_false_by_default
+    assert_equal false, ActiveRecord::Base.include_root_in_json, "include_root_in_json should be false by default but was not"
+  end
+
   def test_serialize_should_be_reversible
     FORMATS.each do |format|
       @serialized = Contact.new.send("to_#{format}")