2 files changed, 17 insertions, 3 deletions
diff --git a/activerecord/lib/active_record/type/decorator.rb b/activerecord/lib/active_record/type/decorator.rb
new file mode 100644
index 0000000000..9fce38ea44
--- /dev/null
+++ b/activerecord/lib/active_record/type/decorator.rb
@@ -0,0 +1,14 @@
+module ActiveRecord
+  module Type
+    module Decorator # :nodoc:
+      def init_with(coder)
+        @subtype = coder['subtype']
+        __setobj__(@subtype)
+      end
+
+      def encode_with(coder)
+        coder['subtype'] = __getobj__
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/type/serialized.rb b/activerecord/lib/active_record/type/serialized.rb
index 5b512433b0..17004b3593 100644
--- a/activerecord/lib/active_record/type/serialized.rb
+++ b/activerecord/lib/active_record/type/serialized.rb
@@ -2,6 +2,7 @@ module ActiveRecord
   module Type
     class Serialized < SimpleDelegator # :nodoc:
       include Mutable
+      include Decorator
 
       attr_reader :subtype, :coder
 
@@ -36,14 +37,13 @@ module ActiveRecord
       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