diff --git a/system/database/drivers/mssql/mssql_driver.php b/system/database/drivers/mssql/mssql_driver.php
index 7b024d4..1ed333d 100644
--- a/system/database/drivers/mssql/mssql_driver.php
+++ b/system/database/drivers/mssql/mssql_driver.php
@@ -465,7 +465,7 @@
 			return "\"{$item}\"";
 		}
 
-		$exceptions = array('AS', '/', '-', '%', '+', '*');
+		$exceptions = array('AS', '/', '-', '%', '+', '*', 'OR', 'IS');
 		
 		foreach ($exceptions as $exception)
 		{