diff --git a/core/modules/simpletest/src/Tests/KernelTestBaseTest.php b/core/modules/simpletest/src/Tests/KernelTestBaseTest.php
index 83135f6..9ad06cf 100644
--- a/core/modules/simpletest/src/Tests/KernelTestBaseTest.php
+++ b/core/modules/simpletest/src/Tests/KernelTestBaseTest.php
@@ -341,7 +341,7 @@ public function testEnableModules() {
     $this->enableModules(['system', 'user']);
     $core = \Drupal::config('core.extension');
     $this->assertEqual(['entity_test' => 0, 'user' => 0, 'system' => 0], $core->get('module'));
-    $this->assertEqual(['current' => \Drupal::VERSION, 'install' => \Drupal::VERSION, 'schema' => NULL], $core->get('versions.user'));
+    $this->assertEqual(['current' => \Drupal::VERSION, 'install' => \Drupal::VERSION, 'schema' => (string) SCHEMA_UNINSTALLED], $core->get('versions.user'));
     $this->assertTrue(\Drupal::moduleHandler()->moduleExists('system'));
   }
 
diff --git a/core/tests/Drupal/KernelTests/KernelTestBaseTest.php b/core/tests/Drupal/KernelTests/KernelTestBaseTest.php
index d3e30db..604711d 100644
--- a/core/tests/Drupal/KernelTests/KernelTestBaseTest.php
+++ b/core/tests/Drupal/KernelTests/KernelTestBaseTest.php
@@ -218,7 +218,7 @@ public function testEnableModules() {
     $this->enableModules(['system', 'user']);
     $core = \Drupal::config('core.extension');
     $this->assertEquals(['user' => 0, 'system' => 0], $core->get('module'));
-    $this->assertEquals(['current' => \Drupal::VERSION, 'install' => \Drupal::VERSION, 'schema' => NULL], $core->get('versions.user'));
+    $this->assertEquals(['current' => \Drupal::VERSION, 'install' => \Drupal::VERSION, 'schema' => (string) SCHEMA_UNINSTALLED], $core->get('versions.user'));
     $this->assertTrue(\Drupal::moduleHandler()->moduleExists('system'));
   }