diff --git a/core/modules/rest/tests/src/Functional/Views/StyleSerializerTest.php b/core/modules/rest/tests/src/Functional/Views/StyleSerializerTest.php
index 6021300953..8747198bf8 100644
--- a/core/modules/rest/tests/src/Functional/Views/StyleSerializerTest.php
+++ b/core/modules/rest/tests/src/Functional/Views/StyleSerializerTest.php
@@ -397,22 +397,13 @@ public function testResponseFormatConfiguration() {
     $this->drupalGet('test/serialize/field', ['query' => ['_format' => 'json']]);
     $this->assertHeader('content-type', 'application/json');
     $this->assertResponse(200, 'A 200 response was returned when JSON was requested.');
-    $headers = $this->drupalGetHeaders();
-    $this->assertEqual($headers['Content-Type'], ['application/json'], 'The header Content-type is correct.');
+
     // Should return a 200.
     $this->drupalGet('test/serialize/field', ['query' => ['_format' => 'xml']]);
     $this->assertHeader('content-type', 'text/xml; charset=UTF-8');
     $this->assertResponse(200, 'A 200 response was returned when XML was requested');
-    $headers = $this->drupalGetHeaders();
-    $this->assertSame(['text/xml; charset=UTF-8'], $headers['Content-Type']);
-    // Should return a 406.
-    $this->drupalGet('test/serialize/field', ['query' => ['_format' => 'html']]);
-    // We want to show the first format by default, see
-    // \Drupal\rest\Plugin\views\style\Serializer::render.
-    $this->assertHeader('content-type', 'application/json');
-    $this->assertResponse(200, 'A 200 response was returned when HTML was requested.');
 
-    // Now configure no format, so all of them should be allowed.
+    // Now configure no format, so both serialization formats should be allowed.
     $this->drupalPostForm($style_options, ['style_options[formats][json]' => '0', 'style_options[formats][xml]' => '0'], t('Apply'));
 
     // Should return a 200.
@@ -423,7 +414,8 @@ public function testResponseFormatConfiguration() {
     $this->drupalGet('test/serialize/field', ['query' => ['_format' => 'xml']]);
     $this->assertHeader('content-type', 'text/xml; charset=UTF-8');
     $this->assertResponse(200, 'A 200 response was returned when XML was requested');
-    // Should return a 406 for HTML.
+
+    // Should return a 406 for HTML still.
     $this->drupalGet('test/serialize/field', ['query' => ['_format' => 'html']]);
     $this->assertHeader('content-type', 'text/html; charset=UTF-8');
     $this->assertResponse(406, 'A 406 response was returned when HTML was requested.');