diff --git a/htdocs/core/class/html.form.class.php b/htdocs/core/class/html.form.class.php
index ee0c35ac3a9..bd87fda5799 100644
--- a/htdocs/core/class/html.form.class.php
+++ b/htdocs/core/class/html.form.class.php
@@ -6095,7 +6095,7 @@ class Form
 				foreach ($array as $key => $value)
 				{
 					$out.= '<option value="'.$key.'"';
-					if (is_array($selected) && ! empty($selected) && in_array($key, $selected) && !empty($key))
+					if (is_array($selected) && ! empty($selected) && in_array($key, $selected) && ((string) $key != ''))
 					{
 						$out.= ' selected';
 					}