diff --git a/_test/tests/inc/io_replaceinfile.test.php b/_test/tests/inc/io_replaceinfile.test.php
index 2e46fc551c49912cf9e94f4170b35c629161ca17..58a29d86bcc7335aa4b87d3155548785db5d9e62 100644
--- a/_test/tests/inc/io_replaceinfile.test.php
+++ b/_test/tests/inc/io_replaceinfile.test.php
@@ -101,9 +101,9 @@ class io_replaceinfile_test extends DokuWikiTest {
     function test_badparam()
     {
         if (class_exists('PHPUnit\Framework\Error\Warning')) {
-            $expect = PHPUnit\Framework\Error\Warning::class; // PHPUnit 6
+            $expect = 'PHPUnit\Framework\Error\Warning'; // PHPUnit 6
         } else {
-            $expect = PHPUnit_Framework_Error_Warning::class; // PHPUnit 5
+            $expect = 'PHPUnit_Framework_Error_Warning'; // PHPUnit 5
         }
         $this->setExpectedException($expect);