diff --git a/lib/active_model/serializer/adapter/flatten_json.rb b/lib/active_model/serializer/adapter/flatten_json.rb
index 397a53b8..17cff8f5 100644
--- a/lib/active_model/serializer/adapter/flatten_json.rb
+++ b/lib/active_model/serializer/adapter/flatten_json.rb
@@ -1,5 +1,3 @@
-require 'active_model/serializer/adapter/json/fragment_cache'
-
 module ActiveModel
   class Serializer
     class Adapter
diff --git a/lib/active_model/serializer/adapter/json_api.rb b/lib/active_model/serializer/adapter/json_api.rb
index 8028a075..39e6815c 100644
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@@ -6,7 +6,6 @@ module ActiveModel
       class JsonApi < Adapter
         def initialize(serializer, options = {})
           super
-          serializer.root = true
           @hash = { data: [] }
 
           if fields = options.delete(:fields)
diff --git a/lib/active_model/serializer/array_serializer.rb b/lib/active_model/serializer/array_serializer.rb
index a5f7b6a1..f88a101a 100644
--- a/lib/active_model/serializer/array_serializer.rb
+++ b/lib/active_model/serializer/array_serializer.rb
@@ -21,7 +21,7 @@ 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)