Index: in-commerce/install/upgrades.php
===================================================================
--- in-commerce/install/upgrades.php	(revision 15468)
+++ in-commerce/install/upgrades.php	(working copy)
@@ -104,7 +104,7 @@
 
 				// clean incomplete orders 5+ hours old
 				// don't use ORDER_STATUS_INCOMPLETE constant, since it's not available upgrade
-				$delete_timestamp = mktime() - (3600 * 5);
+				$delete_timestamp = time() - (3600 * 5);
 				$sql = 'SELECT OrderId FROM ' . TABLE_PREFIX . 'Orders
 							WHERE Status = ' . 0 . '
 							AND OrderDate < ' . $delete_timestamp;