diff --git a/tests/phpunit/local/controllers/maintenance_static_page_test.php b/tests/phpunit/local/controllers/maintenance_static_page_test.php
index dfd6ac5..b2238cc 100644
--- a/tests/phpunit/local/controllers/maintenance_static_page_test.php
+++ b/tests/phpunit/local/controllers/maintenance_static_page_test.php
@@ -453,7 +453,7 @@ class maintenance_static_page_test extends auth_outage_base_testcase {
         $generator = new maintenance_static_page_generator(new DOMDocument(), new maintenance_static_page_io());
         $matches = $generator->get_urls_from_stylesheet($filecontent);
 
-        self::assertIsArray($matches);
+        self::assertInternalType('array', $matches);
         self::assertCount(2, $matches);
         self::assertCount($count, $matches[1]);
     }