1 files changed, 6 insertions, 1 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 eae5eed3a1..b710cf6bdb 100644
--- a/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb
+++ b/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb
@@ -11,7 +11,12 @@ module ActiveRecord
 
         def replace_keys(record)
           super
-          owner[reflection.foreign_type] = record && record.class.base_class.name
+          owner[reflection.foreign_type] = record.class.base_class.name
+        end
+
+        def remove_keys
+          super
+          owner[reflection.foreign_type] = nil
         end
 
         def different_target?(record)