diff --git a/htdocs/accountancy/bookkeeping/thirdparty_lettering_supplier.php b/htdocs/accountancy/bookkeeping/thirdparty_lettering_supplier.php
index 16aa51beded..b5620f3ec25 100644
--- a/htdocs/accountancy/bookkeeping/thirdparty_lettering_supplier.php
+++ b/htdocs/accountancy/bookkeeping/thirdparty_lettering_supplier.php
@@ -4,7 +4,7 @@
  * Copyright (C) 2013      Olivier Geffroy      <jeff@jeffinfo.com>
  * Copyright (C) 2013      Florian Henry	    <florian.henry@open-concept.pro>
  * Copyright (C) 2013-2019 Alexandre Spangaro   <aspangaro@open-dsi.fr>
- * Copyright (C) 2018-2019 Frédéric France      <frederic.france@netlogic.fr>
+ * Copyright (C) 2018-2020 Frédéric France      <frederic.france@netlogic.fr>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -41,7 +41,7 @@ $massaction = GETPOST('massaction', 'alpha');
 $show_files = GETPOST('show_files', 'int');
 $confirm    = GETPOST('confirm', 'alpha');
 $toselect   = GETPOST('toselect', 'array');
-$socid      = GETPOST('socid', 'int') ?GETPOST('socid', 'int') : GETPOST('id', 'int');
+$socid      = GETPOST('socid', 'int') ? ((int) GETPOST('socid', 'int')) : ((int) GETPOST('id', 'int'));
 
 $limit = GETPOST('limit', 'int') ? GETPOST('limit', 'int') : $conf->liste_limit;
 $sortfield = GETPOST("sortfield", 'alpha');