diff --git a/htdocs/core/class/extrafields.class.php b/htdocs/core/class/extrafields.class.php
index 74e8884eb95..bfc7a0511b9 100644
--- a/htdocs/core/class/extrafields.class.php
+++ b/htdocs/core/class/extrafields.class.php
@@ -2477,7 +2477,7 @@ class ExtraFields
 						while ($obj = $this->db->fetch_object($resql)) {
 							$c = new Categorie($this->db);
 							$c->fetch($obj->rowid);
-							if ($mode != 'list') {
+							if ((string) $mode != 'list') {
 								$ways = $c->print_all_ways(); // $ways[0] = "ccc2 >> ccc2a >> ccc2a1" with html formatted text
 								foreach ($ways as $way) {
 									$toprint[] = '<li class="select2-search-choice-dolibarr noborderoncategories'.($mode ? ' '.$mode : '').'"'.($c->color ? ' style="background: #'.$c->color.';"' : ' style="background: #bbb"').'>'.img_object('', 'category').' '.$way.'</li>';
@@ -2491,7 +2491,7 @@ class ExtraFields
 									}
 								}
 
-								$s = '<li class="select2-search-choice-dolibarr noborderoncategories '.$forced_color.($mode ? ' '.$mode : '').'"'.($c->color ? ' style="background: #'.$c->color.';"' : ' style="background: #bbb"').'>';
+								$s = '<li class="select2-search-choice-dolibarr noborderoncategories '.$forced_color.$mode.'"'.($c->color ? ' style="background: #'.$c->color.';"' : ' style="background: #bbb"').'>';
 								if ($numElem >= 2) {
 									$s .= img_object($c->label, 'category', 'class="small"');
 								} else {