diff --git a/htdocs/product/card.php b/htdocs/product/card.php
index 0f37edaf398..0f927f3a6e9 100644
--- a/htdocs/product/card.php
+++ b/htdocs/product/card.php
@@ -703,8 +703,8 @@ if (empty($reshook)) {
 				$object->setCategories($categories);
 
 				if (!empty($backtopage)) {
-					$backtopage = preg_replace('/__ID__/', $object->id, $backtopage); // New method to autoselect parent project after a New on another form object creation
-					$backtopage = preg_replace('/--IDFORBACKTOPAGE--/', $object->id, $backtopage); // New method to autoselect parent after a New on another form object creation
+					$backtopage = preg_replace('/__ID__/', (string) $object->id, $backtopage); // New method to autoselect parent project after a New on another form object creation
+					$backtopage = preg_replace('/--IDFORBACKTOPAGE--/', (string) $object->id, $backtopage); // New method to autoselect parent after a New on another form object creation
 					if (preg_match('/\?/', $backtopage)) {
 						$backtopage .= '&productid='.$object->id; // Old method
 					}