diff --git a/htdocs/core/class/commonobject.class.php b/htdocs/core/class/commonobject.class.php
index b624f20a0b3..18fe31aa4e2 100644
--- a/htdocs/core/class/commonobject.class.php
+++ b/htdocs/core/class/commonobject.class.php
@@ -7531,7 +7531,13 @@ abstract class CommonObject
 			} elseif ($this->isDuration($info))
 			{
 				// $this->{$field} may be null, '', 0, '0', 123, '123'
-				if ($this->{$field} != '' || !empty($info['notnull'])) $queryarray[$field] = (int) $this->{$field};		// If '0', it may be set to null later if $info['notnull'] == -1
+				if ((isset($this->{$field}) && $this->{$field} != '') || !empty($info['notnull'])) {
+					if (!isset($this->{$field})) {
+						$queryarray[$field] = 0;
+					} else {
+						$queryarray[$field] = (int) $this->{$field};		// If '0', it may be set to null later if $info['notnull'] == -1
+					}
+				}
 				else $queryarray[$field] = null;
 			} elseif ($this->isInt($info) || $this->isFloat($info))
 			{