diff --git a/htdocs/knowledgemanagement/knowledgerecord_list.php b/htdocs/knowledgemanagement/knowledgerecord_list.php
index cafb5776cf7..706f103a13d 100644
--- a/htdocs/knowledgemanagement/knowledgerecord_list.php
+++ b/htdocs/knowledgemanagement/knowledgerecord_list.php
@@ -1,6 +1,7 @@
 <?php
-/* Copyright (C) 2007-2017 Laurent Destailleur  <eldy@users.sourceforge.net>
- * Copyright (C) 2021       Frédéric France         <frederic.france@netlogic.fr>
+/* Copyright (C) 2007-2017	Laurent Destailleur		<eldy@users.sourceforge.net>
+ * Copyright (C) 2021		Frédéric France			<frederic.france@netlogic.fr>
+ * Copyright (C) 2023		Anthony Berton			<anthony.berton@bb2a.fr>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -293,7 +294,7 @@ if (!empty($searchCategoryKnowledgemanagementList)) {
 		if (intval($searchCategoryKnowledgemanagement) == -2) {
 			$searchCategoryKnowledgemanagementSqlList[] = "NOT EXISTS (SELECT ck.fk_knowledgemanagement FROM ".MAIN_DB_PREFIX."categorie_knowledgemanagement as ck WHERE t.rowid = ck.fk_knowledgemanagement)";
 		} elseif (intval($searchCategoryKnowledgemanagement) > 0) {
-			if ($searchCategoryKnowledgemanagementOperator == 0) {
+			if (empty($searchCategoryKnowledgemanagementOperator)) {
 				$searchCategoryKnowledgemanagementSqlList[] = " EXISTS (SELECT ck.fk_knowledgemanagement FROM ".MAIN_DB_PREFIX."categorie_knowledgemanagement as ck WHERE t.rowid = ck.fk_knowledgemanagement AND ck.fk_categorie = ".((int) $searchCategoryKnowledgemanagement).")";
 			} else {
 				$listofcategoryid .= ($listofcategoryid ? ', ' : '') .((int) $searchCategoryKnowledgemanagement);