diff -ru a/activerecord/lib/active_record/association_preload.rb b/activerecord/lib/active_record/association_preload.rb
--- a/activerecord/lib/active_record/association_preload.rb	Thu Mar 03 16:57:09 2011 -0700
+++ b/activerecord/lib/active_record/association_preload.rb	Thu Mar 10 11:41:27 2011 -0700
@@ -362,9 +362,9 @@

         if interface = reflection.options[:as]
           parent_type = if reflection.active_record.abstract_class?
-            self.base_class.sti_name
+            self.base_class.name
           else
-            reflection.active_record.sti_name
+            reflection.active_record.name
           end

           conditions = "#{reflection.klass.quoted_table_name}.#{connection.quote_column_name "#{interface}_id"} #{in_or_equals_for_ids(ids)} and #{reflection.klass.quoted_table_name}.#{connection.quote_column_name "#{interface}_type"} = '#{parent_type}'"