diff --git a/setup/setuputils.class.inc.php b/setup/setuputils.class.inc.php
index ba15598d9..da9155220 100644
--- a/setup/setuputils.class.inc.php
+++ b/setup/setuputils.class.inc.php
@@ -2120,6 +2120,7 @@ JS
 			'zlib',
 			'zip',
 			'fileinfo', // N°3123
+			'mbstring', // N°2899
 			'gd', // test image type (always returns false if not installed), image resizing, PDF export
 		];
 	}