diff --git a/system/database/drivers/mysql/mysql_forge.php b/system/database/drivers/mysql/mysql_forge.php
index 1e9145e..f4394c6 100644
--- a/system/database/drivers/mysql/mysql_forge.php
+++ b/system/database/drivers/mysql/mysql_forge.php
@@ -175,13 +175,24 @@
 	 * @param	string	$table	(ignored)
 	 * @return	string
 	 */
-	protected function _process_indexes($table = NULL)
+	protected function _process_indexes($table)
 	{
 		$sql = '';
 
 		for ($i = 0, $c = count($this->keys); $i < $c; $i++)
 		{
-			if ( ! isset($this->fields[$this->keys[$i]]))
+			if (is_array($this->keys[$i]))
+			{
+				for ($i2 = 0, $c2 = count($this->keys[$i]); $i2 < $c2; $i2++)
+				{
+					if ( ! isset($this->fields[$this->keys[$i][$i2]]))
+					{
+						unset($this->keys[$i][$i2]);
+						continue;
+					}
+				}
+			}
+			elseif ( ! isset($this->fields[$this->keys[$i]]))
 			{
 				unset($this->keys[$i]);
 				continue;