diff --git a/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php
index d97d7ae..e0dba4d 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php
@@ -33,11 +33,6 @@
   var $upgradeErrors = array();
 
   /**
-   * Array of modules loaded when the test starts.
-   */
-  var $loadedModules = array();
-
-  /**
    * Flag to indicate whether there are pending updates or not.
    */
   var $pendingUpdates = TRUE;
@@ -86,8 +81,6 @@ protected function setUp() {
     $this->upgradedSite = FALSE;
     $this->upgradeErrors = array();
 
-    $this->loadedModules = module_list();
-
     // Create the database prefix for this test.
     $this->prepareDatabasePrefix();
 
@@ -254,8 +247,7 @@ protected function performUpgrade($register_errors = TRUE) {
     // Reload module list. For modules that are enabled in the test database,
     // but not on the test client, we need to load the code here.
     system_list_reset();
-    $new_modules = array_diff(module_list(), $this->loadedModules);
-    foreach ($new_modules as $module) {
+    foreach (module_list() as $module) {
       drupal_load('module', $module);
     }