1 files changed, 12 insertions, 7 deletions
diff --git a/activerecord/lib/active_record/type/serialized.rb b/activerecord/lib/active_record/type/serialized.rb
index 42bbed7103..3cac03464e 100644
--- a/activerecord/lib/active_record/type/serialized.rb
+++ b/activerecord/lib/active_record/type/serialized.rb
@@ -1,7 +1,8 @@
 module ActiveRecord
   module Type
-    class Serialized < SimpleDelegator # :nodoc:
+    class Serialized < DelegateClass(Type::Value) # :nodoc:
       include Mutable
+      include Decorator
 
       attr_reader :subtype, :coder
 
@@ -12,7 +13,7 @@ module ActiveRecord
       end
 
       def type_cast_from_database(value)
-        if is_default_value?(value)
+        if default_value?(value)
           value
         else
           coder.load(super)
@@ -21,29 +22,33 @@ module ActiveRecord
 
       def type_cast_for_database(value)
         return if value.nil?
-        unless is_default_value?(value)
+        unless default_value?(value)
           super coder.dump(value)
         end
       end
 
+      def changed_in_place?(raw_old_value, value)
+        return false if value.nil?
+        subtype.changed_in_place?(raw_old_value, type_cast_for_database(value))
+      end
+
       def accessor
         ActiveRecord::Store::IndifferentHashAccessor
       end
 
       def init_with(coder)
-        @subtype = coder['subtype']
         @coder = coder['coder']
-        __setobj__(@subtype)
+        super
       end
 
       def encode_with(coder)
-        coder['subtype'] = @subtype
         coder['coder'] = @coder
+        super
       end
 
       private
 
-      def is_default_value?(value)
+      def default_value?(value)
         value == coder.load(nil)
       end
     end