diff --git a/system/database/DB_query_builder.php b/system/database/DB_query_builder.php
index 292621b..355613c 100644
--- a/system/database/DB_query_builder.php
+++ b/system/database/DB_query_builder.php
@@ -1846,6 +1846,7 @@
 		{
 			$this->query($this->_update_batch($this->protect_identifiers($table, TRUE, NULL, FALSE), array_slice($this->qb_set, $i, 100), $this->protect_identifiers($index)));
 			$affected_rows += $this->affected_rows();
+			$this->qb_where = array();
 		}
 
 		$this->_reset_write();