diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index f73f83e..eec9002 100644
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -1754,10 +1754,15 @@ module ActiveRecord
           create_reflection(:has_one, association_id, options, self)
         end
 
+        mattr_accessor :valid_keys_for_has_one_through_association
+        @@valid_keys_for_has_one_through_association = [
+          :class_name, :foreign_key, :remote, :select, :conditions, :order,
+          :include, :dependent, :counter_cache, :extend, :as, :through,
+          :source, :source_type, :validate
+        ]
+
         def create_has_one_through_reflection(association_id, options)
-          options.assert_valid_keys(
-            :class_name, :foreign_key, :remote, :select, :conditions, :order, :include, :dependent, :counter_cache, :extend, :as, :through, :source, :source_type, :validate
-          )
+          options.assert_valid_keys(valid_keys_for_has_one_through_association)
           create_reflection(:has_one, association_id, options, self)
         end
 
diff --git a/activerecord/lib/active_record/autosave_association.rb b/activerecord/lib/active_record/autosave_association.rb
index 8cbae70..b15ddfc 100644
--- a/activerecord/lib/active_record/autosave_association.rb
+++ b/activerecord/lib/active_record/autosave_association.rb
@@ -116,7 +116,7 @@ module ActiveRecord
   module AutosaveAssociation
     extend ActiveSupport::Concern
 
-    ASSOCIATION_TYPES = %w{ has_one belongs_to has_many has_and_belongs_to_many }
+    ASSOCIATION_TYPES = %w{ has_one has_one_through belongs_to has_many has_and_belongs_to_many }
 
     included do
       ASSOCIATION_TYPES.each do |type|