diff --git a/lib/active_model/array_serializer.rb b/lib/active_model/array_serializer.rb
index 7bded54f..6e5e077e 100644
--- a/lib/active_model/array_serializer.rb
+++ b/lib/active_model/array_serializer.rb
@@ -14,9 +14,7 @@ module ActiveModel
 
     def initialize(object, options={})
       @object          = object
-      @root            = options[:root]
-      @root            = self.class._root if @root.nil?
-      @root            = options[:resource_name] if @root.nil?
+      @root            = options.fetch(:root, self.class._root)
       @meta_key        = options[:meta_key] || :meta
       @meta            = options[@meta_key]
       @each_serializer = options[:each_serializer]
@@ -24,6 +22,14 @@ module ActiveModel
     end
     attr_accessor :object, :root, :meta_key, :meta
 
+    def json_key
+      if root.nil?
+        @options[:resource_name]
+      else
+        root
+      end
+    end
+
     def serializable_array
       @object.map do |item|
         serializer = @each_serializer || Serializer.serializer_for(item) || DefaultSerializer
diff --git a/lib/active_model/serializable.rb b/lib/active_model/serializable.rb
index fa4b7d83..c5adb684 100644
--- a/lib/active_model/serializable.rb
+++ b/lib/active_model/serializable.rb
@@ -1,7 +1,7 @@
 module ActiveModel
   module Serializable
     def as_json(options={})
-      if root = options[:root] || self.root
+      if root = options.fetch(:root, json_key)
         hash = { root => serializable_object }
         hash.merge!(serializable_data)
         hash
diff --git a/lib/active_model/serializer.rb b/lib/active_model/serializer.rb
index 175a3d2b..b3d55c1f 100644
--- a/lib/active_model/serializer.rb
+++ b/lib/active_model/serializer.rb
@@ -103,17 +103,18 @@ end
     def initialize(object, options={})
       @object   = object
       @scope    = options[:scope]
-      self.root = options[:root]
+      @root     = options.fetch(:root, self.class._root)
       @meta_key = options[:meta_key] || :meta
       @meta     = options[@meta_key]
     end
-    attr_accessor :object, :scope, :meta_key, :meta
-    attr_reader :root
+    attr_accessor :object, :scope, :meta_key, :meta, :root
 
-    def root=(root)
-      @root = root
-      @root = self.class._root if @root.nil?
-      @root = self.class.root_name if @root == true || @root.nil?
+    def json_key
+      if root == true || root.nil?
+        self.class.root_name
+      else
+        root
+      end
     end
 
     def attributes