diff --git a/htdocs/core/lib/date.lib.php b/htdocs/core/lib/date.lib.php
index cebf9ac7b3e..be7a7c5996b 100644
--- a/htdocs/core/lib/date.lib.php
+++ b/htdocs/core/lib/date.lib.php
@@ -122,12 +122,12 @@ function getServerTimeZoneInt($refgmtdate = 'now')
 function dol_time_plus_duree($time, $duration_value, $duration_unit, $ruleforendofmonth = 0)
 {
 	global $conf;
+	if (empty($duration_value)) {
+		return $time;
+	}
 	if ($duration_unit == 's') {
 		return $time + ($duration_value);
 	}
-	if ($duration_value == 0) {
-		return $time;
-	}
 	if ($duration_unit == 'i') {
 		return $time + (60 * $duration_value);
 	}