diff --git a/core/modules/system/lib/Drupal/system/Tests/Module/ModuleTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Module/ModuleTestBase.php
index b7fd25c..f23204b 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Module/ModuleTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Module/ModuleTestBase.php
@@ -99,7 +99,7 @@ function assertModuleConfig($module) {
       return;
     }
     $module_file_storage = new FileStorage($module_config_dir);
-    $names = $module_file_storage->listAll($module . '.');
+    $names = $module_file_storage->listAll();
 
     // Verify that the config directory is not empty.
     $this->assertTrue($names);