diff --git a/core/modules/simpletest/src/Tests/BrokenSetUpTest.php b/core/modules/simpletest/src/Tests/BrokenSetUpTest.php
index 6621545..dae351b 100644
--- a/core/modules/simpletest/src/Tests/BrokenSetUpTest.php
+++ b/core/modules/simpletest/src/Tests/BrokenSetUpTest.php
@@ -30,6 +30,11 @@ class BrokenSetUpTest extends WebTestBase {
   public static $modules = array('simpletest');
 
   /**
+   * The memory limit for this test, Testing module requires 128M.
+   */
+  protected $memoryUsageTrigger = 128;
+
+  /**
    * The path to the shared trigger file.
    *
    * @var string
diff --git a/core/modules/simpletest/src/Tests/InstallationProfileModuleTestsTest.php b/core/modules/simpletest/src/Tests/InstallationProfileModuleTestsTest.php
index 424469a..4cca66a 100644
--- a/core/modules/simpletest/src/Tests/InstallationProfileModuleTestsTest.php
+++ b/core/modules/simpletest/src/Tests/InstallationProfileModuleTestsTest.php
@@ -31,6 +31,11 @@ class InstallationProfileModuleTestsTest extends WebTestBase {
   protected $adminUser;
 
   /**
+   * The memory limit for this test, Testing module requires 128M.
+   */
+  protected $memoryUsageTrigger = 128;
+
+  /**
    * Use the Testing profile.
    *
    * The Testing profile contains drupal_system_listing_compatible_test.test,
diff --git a/core/modules/simpletest/src/Tests/MissingCheckedRequirementsTest.php b/core/modules/simpletest/src/Tests/MissingCheckedRequirementsTest.php
index e4790f9..667181e 100644
--- a/core/modules/simpletest/src/Tests/MissingCheckedRequirementsTest.php
+++ b/core/modules/simpletest/src/Tests/MissingCheckedRequirementsTest.php
@@ -23,6 +23,11 @@ class MissingCheckedRequirementsTest extends WebTestBase {
    */
   public static $modules = array('simpletest');
 
+  /**
+   * The memory limit for this test, Testing module requires 128M.
+   */
+  protected $memoryUsageTrigger = 128;
+
   protected function setUp() {
     parent::setUp();
     $admin_user = $this->drupalCreateUser(array('administer unit tests'));
diff --git a/core/modules/simpletest/src/Tests/OtherInstallationProfileTestsTest.php b/core/modules/simpletest/src/Tests/OtherInstallationProfileTestsTest.php
index 9cfbfff..74ce9f2 100644
--- a/core/modules/simpletest/src/Tests/OtherInstallationProfileTestsTest.php
+++ b/core/modules/simpletest/src/Tests/OtherInstallationProfileTestsTest.php
@@ -39,6 +39,11 @@ class OtherInstallationProfileTestsTest extends WebTestBase {
   protected $profile = 'minimal';
 
   /**
+   * The memory limit for this test, Testing module requires 128M.
+   */
+  protected $memoryUsageTrigger = 128;
+
+  /**
    * An administrative user with permission to administer unit tests.
    *
    * @var \Drupal\user\UserInterface
diff --git a/core/modules/simpletest/src/Tests/SimpleTestBrowserTest.php b/core/modules/simpletest/src/Tests/SimpleTestBrowserTest.php
index 956d677..cfd7bc4 100644
--- a/core/modules/simpletest/src/Tests/SimpleTestBrowserTest.php
+++ b/core/modules/simpletest/src/Tests/SimpleTestBrowserTest.php
@@ -24,6 +24,11 @@ class SimpleTestBrowserTest extends WebTestBase {
    */
   public static $modules = array('simpletest', 'test_page_test');
 
+  /**
+   * The memory limit for this test, Testing module requires 128M.
+   */
+  protected $memoryUsageTrigger = 128;
+
   public function setUp() {
     parent::setUp();
     // Create and log in an admin user.
diff --git a/core/modules/simpletest/src/Tests/SimpleTestTest.php b/core/modules/simpletest/src/Tests/SimpleTestTest.php
index 2514d9d..fc4e865 100644
--- a/core/modules/simpletest/src/Tests/SimpleTestTest.php
+++ b/core/modules/simpletest/src/Tests/SimpleTestTest.php
@@ -27,6 +27,11 @@ class SimpleTestTest extends WebTestBase {
   public static $modules = array('simpletest', 'test_page_test');
 
   /**
+   * The memory limit for this test, Testing module requires 128M.
+   */
+  protected $memoryUsageTrigger = 128;
+
+  /**
    * The results array that has been parsed by getTestResults().
    *
    * @var array
diff --git a/core/modules/simpletest/src/WebTestBase.php b/core/modules/simpletest/src/WebTestBase.php
index e366017..9c64c20 100644
--- a/core/modules/simpletest/src/WebTestBase.php
+++ b/core/modules/simpletest/src/WebTestBase.php
@@ -62,13 +62,6 @@
   protected $url;
 
   /**
-   * Set to TRUE to ignore memory usage on the child site.
-   *
-   * @var bool
-   */
-  protected $ignoreMemoryUsage = FALSE;
-
-  /**
    * Set to the maximum number of MB of memory usage to allow on the child site.
    *
    * @var int
@@ -1413,7 +1406,7 @@ protected function curlHeaderCallback($curlHandler, $header) {
       // the header.
       call_user_func_array(array(&$this, 'error'), unserialize(urldecode($matches[1])));
     }
-    if (!$this->ignoreMemoryUsage && preg_match('/^X-Drupal-Memory-Peak: (.*)$/', $header, $matches)) {
+    if (preg_match('/^X-Drupal-Memory-Peak: (.*)$/', $header, $matches)) {
       if ((float) $matches[1] >= $this->memoryUsageTrigger) {
         $this->fail(SafeMarkup::format('Child site memory usage (@siteMB) exceeded acceptable maximum (@maxMB) on url @url', [
           '@url' => $this->getUrl(),