diff --git a/htdocs/core/lib/functions.lib.php b/htdocs/core/lib/functions.lib.php
index 1a4aa60a012..c4473d06f7c 100644
--- a/htdocs/core/lib/functions.lib.php
+++ b/htdocs/core/lib/functions.lib.php
@@ -981,9 +981,9 @@ function dol_mktime($hour,$minute,$second,$month,$day,$year,$gm=false,$check=1)
 	//print "- ".$hour.",".$minute.",".$second.",".$month.",".$day.",".$year.",".$_SERVER["WINDIR"]." -";
 
 	// Clean parameters
-	if ($hour   == -1) $hour=0;
-	if ($minute == -1) $minute=0;
-	if ($second == -1) $second=0;
+	if ($hour   == -1 || empty($hour)) $hour=0;
+	if ($minute == -1 || empty($minute)) $minute=0;
+	if ($second == -1 || empty($second)) $second=0;
 
 	// Check parameters
 	if ($check)