diff --git a/lib/active_model/serializer/settings.rb b/lib/active_model/serializer/settings.rb
index 4a3e7c9d..77ac903d 100644
--- a/lib/active_model/serializer/settings.rb
+++ b/lib/active_model/serializer/settings.rb
@@ -1,16 +1,18 @@
+require 'active_support/hash_with_indifferent_access'
+
 module ActiveModel
   class Serializer
     class Settings
       def initialize
-        @data = {}
+        @data = ActiveSupport::HashWithIndifferentAccess.new
       end
 
       def [](key)
-        @data[key.to_s]
+        @data[key]
       end
 
       def []=(key, value)
-        @data[key.to_s] = value
+        @data[key] = value
       end
 
       def each(&block)
@@ -20,6 +22,17 @@ module ActiveModel
       def clear
         @data.clear
       end
+
+      def method_missing(name, *args)
+        return @data[name] if @data.include?(name)
+        match = name.to_s.match(/(.*?)([?=]?)$/)
+        case match[2]
+        when "="
+          @data[match[1]] = args.first
+        when "?"
+          !!@data[match[1]]
+        end
+      end
     end
 
     SETTINGS = Settings.new
diff --git a/test/unit/active_model/serializer/settings_test.rb b/test/unit/active_model/serializer/settings_test.rb
index abd5531b..2a083db8 100644
--- a/test/unit/active_model/serializer/settings_test.rb
+++ b/test/unit/active_model/serializer/settings_test.rb
@@ -43,6 +43,25 @@ module ActiveModel
         ensure
           SETTINGS.clear
         end
+
+        def test_setup_config_accessors
+          ActiveModel::Serializer.setup do |config|
+            config.foo = 'v1'
+            config.bar = 'v2'
+          end
+
+          assert_equal 'v1', SETTINGS.foo
+          assert_equal 'v2', SETTINGS.bar
+        ensure
+          SETTINGS.clear
+        end
+
+        def test_setup_acessor_when_nil
+          assert_nil SETTINGS.foo
+          SETTINGS.foo = 1
+          assert 1, SETTINGS.foo
+          assert_nil SETTINGS.bar
+        end
       end
     end
   end