diff --git a/core/modules/language/src/Tests/LanguageUILanguageNegotiationTest.php b/core/modules/language/src/Tests/LanguageUILanguageNegotiationTest.php
index fb4a3bb..9582be6 100644
--- a/core/modules/language/src/Tests/LanguageUILanguageNegotiationTest.php
+++ b/core/modules/language/src/Tests/LanguageUILanguageNegotiationTest.php
@@ -472,10 +472,13 @@ function testLanguageDomain() {
     $correct_link = 'https://' . $link;
     $this->assertTrue($italian_url == $correct_link, format_string('The _url() function returns the right HTTPS URL (via options) (@url) in accordance with the chosen language', array('@url' => $italian_url)));
 
-    // Test HTTPS via current URL scheme.
+    // Switch from HTTP to HTTPS support.
     $request = Request::create('', 'GET', array(), array(), array(), array('HTTPS' => 'on'));
     $this->container->get('request_stack')->push($request);
     $generator = $this->container->get('url_generator');
+    $generator->clearCache();
+
+    // Test HTTPS via current URL scheme.
     $italian_url = _url('admin', array('language' => $languages['it'], 'script' => ''));
     $correct_link = 'https://' . $link;
     $this->assertTrue($italian_url == $correct_link, format_string('The _url() function returns the right URL (via current URL scheme) (@url) in accordance with the chosen language', array('@url' => $italian_url)));