diff --git a/activerecord/lib/active_record/timestamp.rb b/activerecord/lib/active_record/timestamp.rb
index c6ff4b39fa471d6fdbaaebd1b93330df97bbf05f..a7583f06cc62081e72256dffada9e3eced968931 100644
--- a/activerecord/lib/active_record/timestamp.rb
+++ b/activerecord/lib/active_record/timestamp.rb
@@ -61,7 +61,7 @@ def update(*args) #:nodoc:
     end
 
     def should_record_timestamps?
-      record_timestamps && !partial_updates? || changed?
+      record_timestamps && (!partial_updates? || changed?)
     end
 
     def timestamp_attributes_for_update_in_model