diff --git a/htdocs/install/inc.php b/htdocs/install/inc.php
index 871390d7e31..880a5cb0653 100644
--- a/htdocs/install/inc.php
+++ b/htdocs/install/inc.php
@@ -67,6 +67,8 @@ if (! defined('DONOTLOADCONF') && file_exists($conffile))
 	$result=include_once($conffile);	// Load conf file
 	if ($result) 
 	{
+		if (empty($dolibarr_main_db_type)) $dolibarr_main_db_type='mysql';	// For backward compatibility 
+		
 		// Remove last / or \ on directories or url value
 		if (! empty($dolibarr_main_document_root) && ! ereg('^[\\\/]+$',$dolibarr_main_document_root)) $dolibarr_main_document_root=ereg_replace('[\\\/]+$','',$dolibarr_main_document_root);
 		if (! empty($dolibarr_main_url_root)      && ! ereg('^[\\\/]+$',$dolibarr_main_url_root))      $dolibarr_main_url_root=ereg_replace('[\\\/]+$','',$dolibarr_main_url_root);
@@ -103,6 +105,7 @@ if (! defined('DONOTLOADCONF') && file_exists($conffile))
 		$includeconferror='ErrorBadFormatForConfFile';	
 	}
 }
+
 if (! isset($dolibarr_main_db_prefix) || ! $dolibarr_main_db_prefix) $dolibarr_main_db_prefix='llx_'; 
 define('MAIN_DB_PREFIX',(isset($dolibarr_main_db_prefix)?$dolibarr_main_db_prefix:''));
 define('DOL_DATA_ROOT',(isset($dolibarr_main_data_root)?$dolibarr_main_data_root:''));