diff --git a/activerecord/lib/active_record/attribute_methods/dirty.rb b/activerecord/lib/active_record/attribute_methods/dirty.rb
index 78a941b5d4..439880c1fa 100644
--- a/activerecord/lib/active_record/attribute_methods/dirty.rb
+++ b/activerecord/lib/active_record/attribute_methods/dirty.rb
@@ -41,10 +41,6 @@ module ActiveRecord
         end
       end
 
-      def changed?
-        super || (attributes.keys & self.class.serialized_attributes.keys).present?
-      end
-
     private
       # Wrap write_attribute to remember original attribute value.
       def write_attribute(attr, value)
diff --git a/activerecord/lib/active_record/timestamp.rb b/activerecord/lib/active_record/timestamp.rb
index a7583f06cc..230adf6b2b 100644
--- a/activerecord/lib/active_record/timestamp.rb
+++ b/activerecord/lib/active_record/timestamp.rb
@@ -61,7 +61,7 @@ module ActiveRecord
     end
 
     def should_record_timestamps?
-      record_timestamps && (!partial_updates? || changed?)
+      record_timestamps && (!partial_updates? || changed? || (attributes.keys & self.class.serialized_attributes.keys).present?)
     end
 
     def timestamp_attributes_for_update_in_model