diff --git a/core/modules/system/lib/Drupal/system/Tests/Module/InstallUninstallTest.php b/core/modules/system/lib/Drupal/system/Tests/Module/InstallUninstallTest.php
index 1f47cc9..253b145 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Module/InstallUninstallTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Module/InstallUninstallTest.php
@@ -7,6 +7,8 @@
 
 namespace Drupal\system\Tests\Module;
 
+use Psr\Log\LogLevel;
+
 /**
  * Tests functionality for installing and uninstalling modules.
  */
@@ -98,7 +100,7 @@ public function testInstallUninstall() {
         $this->assertModules(array($module_to_install), TRUE);
         $this->assertModuleTablesExist($module_to_install);
         $this->assertModuleConfig($module_to_install);
-        $this->assertLogMessage('system', "%module module installed.", array('%module' => $module_to_install), WATCHDOG_INFO);
+        $this->assertLogMessage('system', "%module module installed.", array('%module' => $module_to_install), LogLevel::INFO);
       }
 
       // Uninstall the original module, and check appropriate
@@ -167,7 +169,7 @@ protected function assertSuccessfullUninstall($module, $package = 'Core') {
     // module was just uninstalled, since the {watchdog} table won't be there
     // anymore.)
     $this->assertText(t('hook_modules_uninstalled fired for @module', array('@module' => $module)));
-    $this->assertLogMessage('system', "%module module uninstalled.", array('%module' => $module), WATCHDOG_INFO);
+    $this->assertLogMessage('system', "%module module uninstalled.", array('%module' => $module), LogLevel::INFO);
 
     // Check that the module's database tables no longer exist.
     $this->assertModuleTablesDoNotExist($module);
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 0ce14fe..38300d9 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Module/ModuleTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Module/ModuleTestBase.php
@@ -11,6 +11,7 @@
 use Drupal\Core\Database\Database;
 use Drupal\Core\Config\FileStorage;
 use Drupal\simpletest\WebTestBase;
+use Psr\Log\LogLevel;
 
 /**
  * Helper class for module test cases.
@@ -184,7 +185,7 @@ function assertModules(array $modules, $enabled) {
    * @param $link
    *   A link to associate with the message.
    */
-  function assertLogMessage($type, $message, $variables = array(), $severity = WATCHDOG_NOTICE, $link = '') {
+  function assertLogMessage($type, $message, $variables = array(), $severity = LogLevel::NOTICE, $link = '') {
     $count = db_select('watchdog', 'w')
       ->condition('type', $type)
       ->condition('message', $message)