diff --git a/install-dev/upgrade/sql/1.5.0.13.sql b/install-dev/upgrade/sql/1.5.0.13.sql
index 103ed3c04..418a795e2 100644
--- a/install-dev/upgrade/sql/1.5.0.13.sql
+++ b/install-dev/upgrade/sql/1.5.0.13.sql
@@ -1,8 +1,8 @@
 SET NAMES 'utf8';
 
-DROP TABLE `PREFIX_discount`;
-DROP TABLE `PREFIX_discount_type`;
-DROP TABLE `PREFIX_discount_type_lang`;
+DROP TABLE IF EXISTS `PREFIX_discount`;
+DROP TABLE IF EXISTS `PREFIX_discount_type`;
+DROP TABLE IF EXISTS `PREFIX_discount_type_lang`;
 
 /* PHP:add_missing_image_key(); */;