1 files changed, 5 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb b/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb
index 81d4abfa68..b710cf6bdb 100644
--- a/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb
+++ b/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb
@@ -14,6 +14,11 @@ module ActiveRecord
           owner[reflection.foreign_type] = record.class.base_class.name
         end
 
+        def remove_keys
+          super
+          owner[reflection.foreign_type] = nil
+        end
+
         def different_target?(record)
           super || record.class != klass
         end