diff --git a/lib/active_model/serializer.rb b/lib/active_model/serializer.rb
index 4a5f9668..9f62e615 100644
--- a/lib/active_model/serializer.rb
+++ b/lib/active_model/serializer.rb
@@ -169,7 +169,7 @@ module ActiveModel
     end
 
     def json_key
-      self.class.root_name
+      @root || self.class.root_name
     end
 
     def id
diff --git a/lib/active_model/serializer/array_serializer.rb b/lib/active_model/serializer/array_serializer.rb
index a7e27a56..f2f916e5 100644
--- a/lib/active_model/serializer/array_serializer.rb
+++ b/lib/active_model/serializer/array_serializer.rb
@@ -5,9 +5,10 @@ module ActiveModel
       include Enumerable
       delegate :each, to: :@objects
 
-      attr_reader :meta, :meta_key
+      attr_reader :root, :meta, :meta_key
 
       def initialize(objects, options = {})
+        @root = options[:root]
         @resource = objects
         @objects  = objects.map do |object|
           serializer_class = options.fetch(
@@ -26,15 +27,8 @@ module ActiveModel
       end
 
       def json_key
-        if @objects.first
-          @objects.first.json_key.pluralize
-        else
-          @resource.name.underscore.pluralize if @resource.try(:name)
-        end
-      end
-
-      def root=(root)
-        @objects.first.root = root if @objects.first
+        key = root || @objects.first.try(:json_key) || @resource.try(:name).try(:underscore)
+        key.try(:pluralize)
       end
     end
   end
diff --git a/test/action_controller/serialization_test.rb b/test/action_controller/serialization_test.rb
index 82da8a67..d7e3555e 100644
--- a/test/action_controller/serialization_test.rb
+++ b/test/action_controller/serialization_test.rb
@@ -18,6 +18,26 @@ module ActionController
           end
         end
 
+        def render_array_using_custom_root
+          with_adapter ActiveModel::Serializer::Adapter::Json do
+            @profile = Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' })
+            render json: [@profile], root: "custom_root"
+          end
+        end
+
+        def render_array_that_is_empty_using_custom_root
+          with_adapter ActiveModel::Serializer::Adapter::Json do
+            render json: [], root: "custom_root"
+          end
+        end
+
+        def render_object_using_custom_root
+          with_adapter ActiveModel::Serializer::Adapter::Json do
+            @profile = Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' })
+            render json: @profile, root: "custom_root"
+          end
+        end
+
         def render_array_using_implicit_serializer
           array = [
             Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' }),
@@ -169,6 +189,30 @@ module ActionController
         assert_equal expected.to_json, @response.body
       end
 
+      def test_render_array_using_custom_root
+        get :render_array_using_custom_root
+
+        expected =  {custom_roots: [{name: "Name 1", description: "Description 1"}]}
+        assert_equal 'application/json', @response.content_type
+        assert_equal expected.to_json, @response.body
+      end
+
+      def test_render_array_that_is_empty_using_custom_root
+        get :render_array_that_is_empty_using_custom_root
+
+        expected =  {custom_roots: []}
+        assert_equal 'application/json', @response.content_type
+        assert_equal expected.to_json, @response.body
+      end
+
+      def test_render_object_using_custom_root
+        get :render_object_using_custom_root
+
+        expected =  {custom_root: {name: "Name 1", description: "Description 1"}}
+        assert_equal 'application/json', @response.content_type
+        assert_equal expected.to_json, @response.body
+      end
+
       def test_render_json_object_without_serializer
         get :render_json_object_without_serializer
 
diff --git a/test/array_serializer_test.rb b/test/array_serializer_test.rb
index b7ee709c..3eff3ef8 100644
--- a/test/array_serializer_test.rb
+++ b/test/array_serializer_test.rb
@@ -6,7 +6,13 @@ module ActiveModel
       def setup
         @comment = Comment.new
         @post = Post.new
-        @serializer = ArraySerializer.new([@comment, @post], {some: :options})
+        @resource = build_named_collection @comment, @post
+        @serializer = ArraySerializer.new(@resource, {some: :options})
+      end
+
+      def build_named_collection(*resource)
+        resource.define_singleton_method(:name){ 'MeResource' }
+        resource
       end
 
       def test_respond_to_each
@@ -39,15 +45,52 @@ module ActiveModel
         assert_equal @serializer.meta_key, "the meta key"
       end
 
-      def test_json_key_when_resource_is_empty
-        Array.class_eval do
-          def name
-            'PostComment'
-          end
-        end
-        @post_comments = []
-        @serializer = ArraySerializer.new(@post_comments)
-        assert_equal @serializer.json_key, "post_comments"
+      def test_root_default
+        @serializer = ArraySerializer.new([@comment, @post])
+        assert_equal @serializer.root, nil
+      end
+
+      def test_root
+        expected =  'custom_root'
+        @serializer = ArraySerializer.new([@comment, @post], root: expected)
+        assert_equal @serializer.root, expected
+      end
+
+      def test_root_with_no_serializers
+        expected =  'custom_root'
+        @serializer = ArraySerializer.new([], root: expected)
+        assert_equal @serializer.root, expected
+      end
+
+      def test_json_key
+        assert_equal @serializer.json_key, 'comments'
+      end
+
+      def test_json_key_with_resource_with_name_and_no_serializers
+        serializer = ArraySerializer.new(build_named_collection)
+        assert_equal serializer.json_key, 'me_resources'
+      end
+
+      def test_json_key_with_resource_with_nil_name_and_no_serializers
+        resource = []
+        resource.define_singleton_method(:name){ nil }
+        serializer = ArraySerializer.new(resource)
+        assert_equal serializer.json_key, nil
+      end
+
+      def test_json_key_with_resource_without_name_and_no_serializers
+        serializer = ArraySerializer.new([])
+        assert_equal serializer.json_key, nil
+      end
+
+      def test_json_key_with_root
+        serializer = ArraySerializer.new(@resource, root: 'custom_root')
+        assert_equal serializer.json_key, 'custom_roots'
+      end
+
+      def test_json_key_with_root_and_no_serializers
+        serializer = ArraySerializer.new(build_named_collection, root: 'custom_root')
+        assert_equal serializer.json_key, 'custom_roots'
       end
     end
   end
diff --git a/test/serializers/root_test.rb b/test/serializers/root_test.rb
new file mode 100644
index 00000000..05853e39
--- /dev/null
+++ b/test/serializers/root_test.rb
@@ -0,0 +1,19 @@
+require 'test_helper'
+
+module ActiveModel
+  class Serializer
+    class RootTest < Minitest::Test
+
+      def setup
+        @profile = Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' })
+        @profile_serializer = ProfileSerializer.new(@post, {root: 'smth'})
+      end
+
+      def test_overwrite_root
+        setup
+        assert_equal('smth', @profile_serializer.json_key)
+      end
+
+    end
+  end
+end