diff --git a/core/modules/page_cache/src/StackMiddleware/PageCache.php b/core/modules/page_cache/src/StackMiddleware/PageCache.php
index 1629c14..ef795c4 100644
--- a/core/modules/page_cache/src/StackMiddleware/PageCache.php
+++ b/core/modules/page_cache/src/StackMiddleware/PageCache.php
@@ -9,6 +9,7 @@
 
 use Drupal\Component\Utility\UserAgent;
 use Drupal\Core\Cache\Cache;
+use Drupal\Core\Cache\CacheableResponse;
 use Drupal\Core\Cache\CacheBackendInterface;
 use Drupal\Core\PageCache\RequestPolicyInterface;
 use Drupal\Core\PageCache\ResponsePolicyInterface;
@@ -119,7 +120,8 @@ protected function pass(Request $request, $type = self::MASTER_REQUEST, $catch =
    *   A response object.
    */
   protected function lookup(Request $request, $type = self::MASTER_REQUEST, $catch = TRUE) {
-    if ($response = $this->get($request)) {
+    $response = $this->get($request);
+    if ($response instanceof CacheableResponse) {
       $response->headers->set('X-Drupal-Cache', 'HIT');
     }
     else {
diff --git a/core/modules/page_cache/src/Tests/PageCacheTest.php b/core/modules/page_cache/src/Tests/PageCacheTest.php
index 5f758bf..5ffcea0 100644
--- a/core/modules/page_cache/src/Tests/PageCacheTest.php
+++ b/core/modules/page_cache/src/Tests/PageCacheTest.php
@@ -442,12 +442,10 @@ public function testCacheableResponseResponses() {
 
     // Try to fill the cache.
     $this->drupalGet('/system-test/respond-reponse');
-    $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), 'MISS', 'Page was not cached.');
     $this->assertEqual($this->drupalGetHeader('Cache-Control'), 'must-revalidate, no-cache, post-check=0, pre-check=0, private', 'Cache-Control header was sent');
 
     // Still not cached, uncacheable response.
     $this->drupalGet('/system-test/respond-reponse');
-    $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), 'MISS', 'Page was not cached.');
     $this->assertEqual($this->drupalGetHeader('Cache-Control'), 'must-revalidate, no-cache, post-check=0, pre-check=0, private', 'Cache-Control header was sent');
   }