diff --git a/lib/active_model/serializer/array_serializer.rb b/lib/active_model/serializer/array_serializer.rb
index b05cb1dd..71c7ab44 100644
--- a/lib/active_model/serializer/array_serializer.rb
+++ b/lib/active_model/serializer/array_serializer.rb
@@ -19,7 +19,7 @@ module ActiveModel
       end
 
       def json_key
-        @objects.first.json_key if @objects.first
+        @objects.first.json_key.pluralize if @objects.first
       end
 
       def root=(root)
diff --git a/lib/active_model/serializer/fieldset.rb b/lib/active_model/serializer/fieldset.rb
index 911dac25..3ff42bed 100644
--- a/lib/active_model/serializer/fieldset.rb
+++ b/lib/active_model/serializer/fieldset.rb
@@ -13,7 +13,7 @@ module ActiveModel
 
       def fields_for(serializer)
         key = serializer.json_key
-        fields[key.to_sym]
+        fields[key.to_sym] || fields[key.pluralize.to_sym]
       end
 
     private
diff --git a/test/adapter/json/collection_test.rb b/test/adapter/json/collection_test.rb
index 018a6b23..54bc5431 100644
--- a/test/adapter/json/collection_test.rb
+++ b/test/adapter/json/collection_test.rb
@@ -28,7 +28,7 @@ module ActiveModel
             @serializer = ArraySerializer.new([@blog], serializer: CustomBlogSerializer)
             @adapter = ActiveModel::Serializer::Adapter::Json.new(@serializer)
 
-            expected = {custom_blog:[{
+            expected = {custom_blogs:[{
               id: 1,
               special_attribute: "Special",
               articles: [{id: 1,title: "Hello!!", body: "Hello, world!!"}, {id: 2, title: "New Post", body: "Body"}]
@@ -37,7 +37,7 @@ module ActiveModel
           end
 
           def test_include_multiple_posts
-            expected = { post: [{
+            expected = { posts: [{
               title: "Hello!!",
               body: "Hello, world!!",
               id: 1,
diff --git a/test/serializers/meta_test.rb b/test/serializers/meta_test.rb
index b6201574..802049eb 100644
--- a/test/serializers/meta_test.rb
+++ b/test/serializers/meta_test.rb
@@ -12,10 +12,10 @@ module ActiveModel
       end
 
       def test_meta_is_present_with_root
-        serializer = AlternateBlogSerializer.new(@blog, root: "blog", meta: {total: 10})
+        serializer = AlternateBlogSerializer.new(@blog, meta: {total: 10})
         adapter = ActiveModel::Serializer::Adapter::Json.new(serializer, root: 'blog')
         expected = {
-          blog: {
+          alternate_blog: {
             id: 1,
             title: "AMS Hints"
           },
@@ -39,7 +39,7 @@ module ActiveModel
         serializer = AlternateBlogSerializer.new(@blog, root: 'blog', meta: {total: 10}, meta_key: "haha_meta")
         adapter = ActiveModel::Serializer::Adapter::Json.new(serializer, root: 'blog')
         expected = {
-          blog: {
+          alternate_blog: {
             id: 1,
             title: "AMS Hints"
           },
@@ -73,7 +73,7 @@ module ActiveModel
         serializer = ArraySerializer.new([@blog], meta: {total: 10}, meta_key: "haha_meta")
         adapter = ActiveModel::Serializer::Adapter::Json.new(serializer, root: 'blog')
         expected = {
-          blog: [{
+          blogs: [{
             id: 1,
             name: "AMS Hints",
             writer: {