diff --git a/htdocs/core/class/commonobject.class.php b/htdocs/core/class/commonobject.class.php
index dd2973cb1fb..750fbc59135 100644
--- a/htdocs/core/class/commonobject.class.php
+++ b/htdocs/core/class/commonobject.class.php
@@ -2745,7 +2745,7 @@ abstract class CommonObject
 	{
         // phpcs:enable
         $positionfield = 'rang';
-		if ($this->table_element = 'bom') $positionfield = 'position';
+		if ($this->table_element == 'bom') $positionfield = 'position';
 
 		// Search the last rang with fk_parent_line
 		if ($fk_parent_line)