diff --git a/src/lib/Query/Common/QueryConverter/NativeQueryConverter.php b/src/lib/Query/Common/QueryConverter/NativeQueryConverter.php
index 5f14ccb..759607c 100644
--- a/src/lib/Query/Common/QueryConverter/NativeQueryConverter.php
+++ b/src/lib/Query/Common/QueryConverter/NativeQueryConverter.php
@@ -68,7 +68,7 @@ public function convert(Query $query, array $languageSettings = [])
     {
         $params = [
             'q' => '{!lucene}' . $this->criterionVisitor->visit($query->query),
-            'fq' => '{!lucene}' . ($query->filter ? $this->criterionVisitor->visit($query->filter) : ''),
+            'fq' => '{!lucene}' . ($query->filter !== null ? $this->criterionVisitor->visit($query->filter) : ''),
             'sort' => $this->getSortClauses($query->sortClauses),
             'start' => $query->offset,
             'rows' => $query->limit,