diff --git a/activerecord/lib/active_record/associations/belongs_to_association.rb b/activerecord/lib/active_record/associations/belongs_to_association.rb
index ec8deca8061be..cd9d4154b2276 100644
--- a/activerecord/lib/active_record/associations/belongs_to_association.rb
+++ b/activerecord/lib/active_record/associations/belongs_to_association.rb
@@ -111,7 +111,7 @@ def require_counter_update?
         def replace_keys(record, force: false)
           target_key = record ? record._read_attribute(primary_key(record.class)) : nil
 
-          if force || owner[reflection.foreign_key] != target_key
+          if force || owner._read_attribute(reflection.foreign_key) != target_key
             owner[reflection.foreign_key] = target_key
           end
         end
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 a0d5522fa04b0..15e6ce1e9fe0f 100644
--- a/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb
+++ b/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb
@@ -19,7 +19,7 @@ def replace_keys(record, force: false)
 
           target_type = record ? record.class.polymorphic_name : nil
 
-          if force || owner[reflection.foreign_type] != target_type
+          if force || owner._read_attribute(reflection.foreign_type) != target_type
             owner[reflection.foreign_type] = target_type
           end
         end