diff --git a/htdocs/core/class/commonobject.class.php b/htdocs/core/class/commonobject.class.php
index b84d31ddae3..b4426a02f74 100644
--- a/htdocs/core/class/commonobject.class.php
+++ b/htdocs/core/class/commonobject.class.php
@@ -6291,7 +6291,7 @@ abstract class CommonObject
 			if (! empty($this->fields[$key]['foreignkey']) && $values[$key] == '-1') $values[$key]='';
 
 			//var_dump($key.'-'.$values[$key].'-'.($this->fields[$key]['notnull'] == 1));
-			if ($this->fields[$key]['notnull'] == 1 && ! isset($values[$key]) && is_null($val['default']))
+			if (isset($this->fields[$key]['notnull']) && $this->fields[$key]['notnull'] == 1 && ! isset($values[$key]) && is_null($val['default']))
 			{
 				$error++;
 				$this->errors[]=$langs->trans("ErrorFieldRequired", $this->fields[$key]['label']);