diff --git a/htdocs/admin/prelevement.php b/htdocs/admin/prelevement.php
index 2f942410787..4fba501b305 100644
--- a/htdocs/admin/prelevement.php
+++ b/htdocs/admin/prelevement.php
@@ -250,9 +250,10 @@ print '</td></tr>';
 //ADDDAYS
 print '<tr class="pair"><td>'.$langs->trans("ADDDAYS").'</td>';
 print '<td class="left">';
-if (! $conf->global->PRELEVEMENT_ADDDAYS) $conf->global->PRELEVEMENT_ADDDAYS=0;
+if (empty($conf->global->PRELEVEMENT_ADDDAYS)) $conf->global->PRELEVEMENT_ADDDAYS=0;
 print '<input type="text" name="PRELEVEMENT_ADDDAYS" value="'.$conf->global->PRELEVEMENT_ADDDAYS.'" size="15" ></td>';
 print '</td></tr>';
+
 print '</table>';
 print '<br>';