diff --git a/core/lib/Drupal/Component/Assertion/Handle.php b/core/lib/Drupal/Component/Assertion/Handle.php
index 3912156..2f4ee3e 100644
--- a/core/lib/Drupal/Component/Assertion/Handle.php
+++ b/core/lib/Drupal/Component/Assertion/Handle.php
@@ -57,7 +57,7 @@ public static function register() {
 
     if (version_compare(PHP_VERSION, '7.0.0-dev') < 0) {
       // PHP 5 - create a handler to throw the exception directly.
-      assert_options(ASSERT_CALLBACK, function($file, $line, $code, $message) {
+      assert_options(ASSERT_CALLBACK, function($file, $line, $code, $message = '') {
         if (empty($message)) {
           $message = $code;
         }
diff --git a/core/modules/simpletest/src/Tests/SimpleTestTest.php b/core/modules/simpletest/src/Tests/SimpleTestTest.php
index c3758a7..6c49ca7 100644
--- a/core/modules/simpletest/src/Tests/SimpleTestTest.php
+++ b/core/modules/simpletest/src/Tests/SimpleTestTest.php
@@ -173,6 +173,13 @@ function stubTest() {
     catch (\AssertionError $e) {
       $this->assertEqual($e->getMessage(), 'Lorem Ipsum', 'Runtime assertions Enabled and running.');
     }
+    try {
+      assert('FALSE');
+      $this->fail('Runtime assertions are not working.');
+    }
+    catch (\AssertionError $e) {
+      $this->assertEqual($e->getMessage(), 'FALSE', 'Runtime assertions Enabled and running.');
+    }
     // This causes the second of the sixteen passes asserted in
     // confirmStubResults().
     $this->pass($this->passMessage);