diff --git a/htdocs/core/class/html.form.class.php b/htdocs/core/class/html.form.class.php
index 04182b53a66..aab16079aef 100644
--- a/htdocs/core/class/html.form.class.php
+++ b/htdocs/core/class/html.form.class.php
@@ -7072,7 +7072,7 @@ class Form
 				$arrayofdateof = $adddateof;
 			}
 			foreach ($arrayofdateof as $valuedateof) {
-				$tmpadddateof = $valuedateof['adddateof'];
+				$tmpadddateof = $valuedateof['adddateof'] != '' ? $valuedateof['adddateof'] : 0;
 				$tmplabeladddateof = $valuedateof['labeladddateof'];
 				$tmparray = dol_getdate($tmpadddateof);
 				if (empty($tmplabeladddateof)) {