diff --git a/htdocs/admin/debugbar.php b/htdocs/admin/debugbar.php
index b6002d1a4df..8a72e3e40c8 100644
--- a/htdocs/admin/debugbar.php
+++ b/htdocs/admin/debugbar.php
@@ -77,10 +77,17 @@ $form=new Form($db);
 
 $linkback='<a href="'.DOL_URL_ROOT.'/admin/modules.php?restore_lastsearch_values=1">'.$langs->trans("BackToModuleList").'</a>';
 print load_fiche_titre($langs->trans("DebugBarSetup"), $linkback, 'title_setup');
-print '<br>';
 
 //print load_fiche_titre($langs->trans("DebugBar"));
 
+if (! function_exists('mb_check_encoding'))
+{
+    $langs->load("errors");
+    print info_admin($langs->trans("ErrorPHPNeedModule", 'mbstring'), 0, 0, 'error');
+}
+
+print '<br>';
+
 // Level
 print '<form action="'.$_SERVER["PHP_SELF"].'" method="post">';
 print '<input type="hidden" name="token" value="'.$_SESSION['newtoken'].'">';