diff --git a/activerecord/lib/active_record/association_preload.rb b/activerecord/lib/active_record/association_preload.rb
index f13c250..872f365 100644
--- a/activerecord/lib/active_record/association_preload.rb
+++ b/activerecord/lib/active_record/association_preload.rb
@@ -356,7 +356,7 @@ module ActiveRecord
         table_name = reflection.klass.quoted_table_name
 
         if interface = reflection.options[:as]
-          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"} = '#{self.base_class.sti_name}'"
+          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"} = '#{self.base_class.name}'"
         else
           foreign_key = reflection.primary_key_name
           conditions = "#{reflection.klass.quoted_table_name}.#{foreign_key} #{in_or_equals_for_ids(ids)}"