diff --git a/htdocs/core/lib/functions.lib.php b/htdocs/core/lib/functions.lib.php
index 61a603f48bd..1eb72d50455 100644
--- a/htdocs/core/lib/functions.lib.php
+++ b/htdocs/core/lib/functions.lib.php
@@ -10422,7 +10422,7 @@ function dolGetButtonAction($label, $html = '', $actionType = 'default', $url =
 	global $hookmanager, $action, $object, $langs;
 
 	//var_dump($params);
-	if ($params['isDropdown'])
+	if (isset($params['isDropdown']))
 		$class = "dropdown-item";
 	else {
 		$class = 'butAction';