diff -u b/core/modules/page_cache/tests/src/Functional/PageCacheTest.php b/core/modules/page_cache/tests/src/Functional/PageCacheTest.php
--- b/core/modules/page_cache/tests/src/Functional/PageCacheTest.php
+++ b/core/modules/page_cache/tests/src/Functional/PageCacheTest.php
@@ -583,46 +583,31 @@
 
     foreach ($tests as list($url_raw, $url_normalized)) {
       // Initialize cache on raw URL.
-      $this->assertResponseHeader('X-Drupal-Cache', 'MISS', $url_raw);
+      $headers = $this->getHeaders($url_raw);
+      $this->assertEquals('MISS', $headers['X-Drupal-Cache']);
+
       // Ensure cache was set.
-      $this->assertResponseHeader('X-Drupal-Cache', 'HIT', $url_raw, "Cache was set for {$url_raw} URL.");
+      $headers = $this->getHeaders($url_raw);
+      $this->assertEquals('HIT', $headers['X-Drupal-Cache'], "Cache was set for {$url_raw} URL.");
+
       // Check if the normalized URL is not cached.
-      $this->assertResponseHeader('X-Drupal-Cache', 'MISS', $url_normalized, "Cache is missing for {$url_normalized} URL.");
+      $headers = $this->getHeaders($url_normalized);
+      $this->assertEquals('MISS', $headers['X-Drupal-Cache'], "Cache is missing for {$url_normalized} URL.");
     }
   }
 
   /**
-   * Asserts that the response header has the expected value.
-   *
-   * @param string $header
-   *   Header name.
-   * @param string $expected
-   *   Expected value of the header.
-   * @param string $url
-   *   The url to test.
-   * @param string $message
-   *   (optional) A message to display with the assertion.
-   */
-  protected function assertResponseHeader($header, $expected, $url, $message = '') {
-    $headers = $this->getHeaders($url);
-    $this->assertSame($expected, $headers[$header], $message);
-  }
-
-  /**
    * Retrieves only the headers for an absolute path.
    *
-   * This is a simplified re-implementation of a drupalHead() that
-   * executes a cURL request without any URL modifications (Guzzle always
-   * normalizes URLs and therefore doesn't allow to test all possible edge
-   * cases).
+   * Executes a cURL request without any modifications to the given URL.
+   * Note that the Guzzle always normalizes URLs which prevents testing all
+   * possible edge cases.
    *
    * @param string $url
    *   The URL to load into internal browser.
    *
    * @return array
    *   Array of headers.
-   *
-   * @see \Drupal\simpletest\WebTestBase::drupalHead()
    */
   protected function getHeaders($url) {
     $ch = curl_init();