diff --git a/tests/php/Publisher/FilesystemPublisherTest.php b/tests/php/Publisher/FilesystemPublisherTest.php
index eae570b..bed0857 100644
--- a/tests/php/Publisher/FilesystemPublisherTest.php
+++ b/tests/php/Publisher/FilesystemPublisherTest.php
@@ -140,7 +140,7 @@ public function testUrlToPathWithDomainBasedCaching(): void
 
     public function testMenu2LinkingMode(): void
     {
-        SSViewer::set_themes(null);
+        SSViewer::set_themes([]);
 
         $reflection = new \ReflectionClass(FilesystemPublisher::class);
         $urlToPath = $reflection->getMethod('URLtoPath');