diff --git a/htdocs/core/class/commonobject.class.php b/htdocs/core/class/commonobject.class.php
index b86ea4fb650..022862e751b 100644
--- a/htdocs/core/class/commonobject.class.php
+++ b/htdocs/core/class/commonobject.class.php
@@ -12,7 +12,7 @@
  * Copyright (C) 2017      ATM Consulting       <support@atm-consulting.fr>
  * Copyright (C) 2017-2019 Nicolas ZABOURI      <info@inovea-conseil.com>
  * Copyright (C) 2017      Rui Strecht		    <rui.strecht@aliartalentos.com>
- * Copyright (C) 2018-2020 Frédéric France      <frederic.france@netlogic.fr>
+ * Copyright (C) 2018-2021 Frédéric France      <frederic.france@netlogic.fr>
  * Copyright (C) 2018      Josep Lluís Amador   <joseplluis@lliuretic.cat>
  * Copyright (C) 2021      Gauthier VERDOL   	<gauthier.verdol@atm-consulting.fr>
  *
@@ -738,11 +738,11 @@ abstract class CommonObject
 		}
 		if ($this->element == 'contact') {
 			$contactid = $this->id;
-			$thirdpartyid = $object->fk_soc;
+			$thirdpartyid = empty($object->fk_soc) ? 0 : $object->fk_soc;
 		}
 		if ($this->element == 'user') {
 			$contactid = $this->contact_id;
-			$thirdpartyid = $object->fk_soc;
+			$thirdpartyid = empty($object->fk_soc) ? 0 : $object->fk_soc;
 		}
 
 		$out = '';