diff --git a/htdocs/public/members/new.php b/htdocs/public/members/new.php
index 1b0adea71dd..f3a364339b3 100644
--- a/htdocs/public/members/new.php
+++ b/htdocs/public/members/new.php
@@ -227,8 +227,8 @@ if (empty($reshook) && $action == 'add') {
 		$langs->load("errors");
 		$errmsg .= $langs->trans("ErrorBadEMail", GETPOST('email'))."<br>\n";
 	}
-	$birthday = dol_mktime(GETPOST('birthhour', 'int'), GETPOST('birthmin', 'int'), GETPOST('birthsec', 'int'), GETPOST('birthmonth', 'int'), GETPOST('birthday', 'int'), GETPOST('birthyear', 'int'));
-	if (GETPOSTISSET('birthmonth') && empty($birthday)) {
+	$birthday = dol_mktime(GETPOST("birthhour", 'int'), GETPOST("birthmin", 'int'), GETPOST("birthsec", 'int'), GETPOST("birthmonth", 'int'), GETPOST("birthday", 'int'), GETPOST("birthyear", 'int'));
+	if (GETPOST("birthmonth") && empty($birthday)) {
 		$error++;
 		$langs->load("errors");
 		$errmsg .= $langs->trans("ErrorBadDateFormat")."<br>\n";