diff --git a/core/tests/Drupal/Tests/Core/DrupalKernel/TrustedHostsTest.php b/core/tests/Drupal/Tests/Core/DrupalKernel/TrustedHostsTest.php
index a3ce0df..c1082f8 100644
--- a/core/tests/Drupal/Tests/Core/DrupalKernel/TrustedHostsTest.php
+++ b/core/tests/Drupal/Tests/Core/DrupalKernel/TrustedHostsTest.php
@@ -44,19 +44,23 @@ public function providerTestTrustedHosts() {
 
     // Test our hardcoded defaults for local development with non-production
     // server configurations.
-    $data[] = ['localhost', '', '', TRUE];
-    $data[] = ['localhost.d8', '', '', TRUE];
-    $data[] = ['d8.local', '', '', TRUE];
+    $data[] = ['localhost', '', 'localhost is trusted', TRUE];
+    $data[] = ['localhost.d8', '', 'localhost.d8 is trusted', TRUE];
+    $data[] = ['d8.local', '', 'd8.local is trusted', TRUE];
 
     // Tests canonical URL
-    $data[] = ['www.example.com', 'www.example.com', '', TRUE];
+    $data[] = ['www.example.com', 'www.example.com', 'canonical URL is trusted', TRUE];
+
+    // Tests missing hostname for HTTP/1.0 compatability where the Host
+    // header is optional
+    $data[] = [NULL, 'www.example.com', 'empty Host is valid', TRUE];
 
     // Tests mismatches
-    $data[] = ['example.com', 'www.example.com', '', FALSE];
-    $data[] = ['subdomain.example.com', 'www.example.com', '', FALSE];
-    $data[] = ['www.example.org', 'www.example.com', '', FALSE];
-    $data[] = ['example.org', 'www.example.com', '', FALSE];
-    $data[] = ['www.blackhat.com', 'www.example.com', '', FALSE];
+    $data[] = ['example.com', 'www.example.com', 'non-canonical host is not trusted', FALSE];
+    $data[] = ['subdomain.example.com', 'www.example.com', 'host with subdomain is not trusted', FALSE];
+    $data[] = ['www.example.org', 'www.example.com', 'host with different TLD is not trusted', FALSE];
+    $data[] = ['example.org', 'www.example.com', 'host with different TLD is not trusted', FALSE];
+    $data[] = ['www.blackhat.com', 'www.example.com', 'unspecified host is untrusted', FALSE];
 
     return $data;
   }
@@ -80,7 +84,10 @@ public function testTrustedHostsWithSettings($host, $server_name, $message, $exp
 
     $request = new Request();
 
-    $request->headers->set('HOST', $host);
+    if (!empty($host)) {
+      $request->headers->set('HOST', $host);
+    }
+
     $request->server->set('SERVER_NAME', $server_name);
 
     $valid_host = DrupalKernel::setupTrustedHosts($request);
@@ -96,21 +103,25 @@ public function providerTestTrustedHostsWithSettings() {
 
     // Test our hardcoded defaults for local development with non-production
     // server configurations.
-    $data[] = ['localhost', '', '', TRUE];
-    $data[] = ['localhost.d8', '', '', TRUE];
-    $data[] = ['d8.local', '', '', TRUE];
+    $data[] = ['localhost', '', 'localhost is trusted', TRUE];
+    $data[] = ['localhost.d8', '', 'localhost.d8 is trusted', TRUE];
+    $data[] = ['d8.local', '', 'd8.local is trusted', TRUE];
 
     // Tests canonical URL
-    $data[] = ['www.example.com', 'www.example.com', '', TRUE];
+    $data[] = ['www.example.com', 'www.example.com', 'canonical URL is trusted', TRUE];
+
+    // Tests missing hostname for HTTP/1.0 compatability where the Host
+    // header is optional
+    $data[] = [NULL, 'www.example.com', 'empty Host is valid', TRUE];
 
     // Tests the additional paterns from the settings.
-    $data[] = ['example.com', 'www.example.com', '', TRUE];
-    $data[] = ['subdomain.example.com', 'www.example.com', '', TRUE];
-    $data[] = ['www.example.org', 'www.example.com', '', TRUE];
-    $data[] = ['example.org', 'www.example.com', '', TRUE];
+    $data[] = ['example.com', 'www.example.com', 'host from settings is trusted', TRUE];
+    $data[] = ['subdomain.example.com', 'www.example.com', 'host from settings is trusted', TRUE];
+    $data[] = ['www.example.org', 'www.example.com', 'host from settings is trusted', TRUE];
+    $data[] = ['example.org', 'www.example.com', 'host from settings is trusted', TRUE];
 
     // Tests mismatches
-    $data[] = ['www.blackhat.com', 'www.example.com', '', FALSE];
+    $data[] = ['www.blackhat.com', 'www.example.com', 'unspecified host is untrusted', FALSE];
 
     return $data;
   }