diff --git a/htdocs/core/class/html.form.class.php b/htdocs/core/class/html.form.class.php
index 59ad9db8377..beb884f39bc 100644
--- a/htdocs/core/class/html.form.class.php
+++ b/htdocs/core/class/html.form.class.php
@@ -7821,6 +7821,8 @@ class Form
 			if ($tmpfieldstoshow) {
 				$fieldstoshow = $tmpfieldstoshow;
 			}
+		} else if ($objecttmp->element === 'category') {
+			$fieldstoshow = 't.label';
 		} else {
 			// For backward compatibility
 			$objecttmp->fields['ref'] = array('type'=>'varchar(30)', 'label'=>'Ref', 'showoncombobox'=>1);