diff --git a/htdocs/core/class/html.formprojet.class.php b/htdocs/core/class/html.formprojet.class.php
index 47bbdec0fb2..e6a580a7f71 100644
--- a/htdocs/core/class/html.formprojet.class.php
+++ b/htdocs/core/class/html.formprojet.class.php
@@ -372,7 +372,7 @@ class FormProjets
 				include_once DOL_DOCUMENT_ROOT.'/core/lib/ajax.lib.php';
 				$comboenhancement = ajax_combobox($htmlname, '', 0, $forcefocus);
 				$out .= $comboenhancement;
-				$morecss = 'minwidth200 maxwidth500';
+				$morecss .= ' minwidth200 maxwidth500';
 			}
 
 			if (empty($option_only)) {