diff --git a/application/cmdbabstract.class.inc.php b/application/cmdbabstract.class.inc.php
index 497072390..87a18f2da 100644
--- a/application/cmdbabstract.class.inc.php
+++ b/application/cmdbabstract.class.inc.php
@@ -2508,7 +2508,7 @@ HTML;
 						$oForm = $value->GetForm($sFormPrefix);
 					} else if ($sAttDefEditClass === 'FormField') {
 						$sFormId = 'ff_'.$oAttDef->GetCode();
-						if (false === is_null($sFormPrefix)) {
+						if (false === utils::IsNotNullOrEmptyString($sFormPrefix)) {
 							$sFormId = $sFormPrefix.$sFormId;
 						}