diff --git a/core/modules/page_cache/src/Tests/PageCacheTest.php b/core/modules/page_cache/src/Tests/PageCacheTest.php
index 421ebf1..b4c0148 100644
--- a/core/modules/page_cache/src/Tests/PageCacheTest.php
+++ b/core/modules/page_cache/src/Tests/PageCacheTest.php
@@ -221,8 +221,10 @@ function testPageCache() {
     $this->assertEqual($this->drupalGetHeader('Foo'), 'bar', 'Custom header was sent.');
 
     // Check replacing default headers.
+    Cache::invalidateTags(['rendered']);
     $this->drupalGet('system-test/set-header', array('query' => array('name' => 'Expires', 'value' => 'Fri, 19 Nov 2008 05:00:00 GMT')));
     $this->assertEqual($this->drupalGetHeader('Expires'), 'Fri, 19 Nov 2008 05:00:00 GMT', 'Default header was replaced.');
+    Cache::invalidateTags(['rendered']);
     $this->drupalGet('system-test/set-header', array('query' => array('name' => 'Vary', 'value' => 'User-Agent')));
     $this->assertEqual(strtolower($this->drupalGetHeader('Vary')), 'user-agent,accept-encoding', 'Default header was replaced.');