diff --git a/core/modules/simpletest/src/WebTestBase.php b/core/modules/simpletest/src/WebTestBase.php
index 7e1b168..850670c 100644
--- a/core/modules/simpletest/src/WebTestBase.php
+++ b/core/modules/simpletest/src/WebTestBase.php
@@ -2743,7 +2743,7 @@ protected function buildUrl($path, array $options = array()) {
     // The URL assembler service is not necessarily available yet; e.g., in
     // interactive installer tests.
     elseif ($this->container->has('unrouted_url_assembler')) {
-      return Url::fromUri('base:://' . $path, $options)->setAbsolute()->toString();
+      return Url::fromUri('base://' . $path, $options)->setAbsolute()->toString();
     }
     else {
       return $this->getAbsoluteUrl($path);
diff --git a/core/modules/system/src/Tests/Menu/AssertBreadcrumbTrait.php b/core/modules/system/src/Tests/Menu/AssertBreadcrumbTrait.php
index 35ddec4..51fcf29 100644
--- a/core/modules/system/src/Tests/Menu/AssertBreadcrumbTrait.php
+++ b/core/modules/system/src/Tests/Menu/AssertBreadcrumbTrait.php
@@ -71,7 +71,7 @@ protected function assertBreadcrumbParts($trail) {
       foreach ($trail as $path => $title) {
         // If the path is empty or does not start with a leading /, assume it
         // is an internal path that needs to be passed through _url().
-        $url = $path == '' || $path[0] != '/' ? Url::fromUri('base:://' . $path)->toString($path) : $path;
+        $url = $path == '' || $path[0] != '/' ? Url::fromUri('base://' . $path)->toString($path) : $path;
         $part = array_shift($parts);
         $pass = ($pass && $part['href'] === $url && $part['text'] === String::checkPlain($title));
       }
diff --git a/core/modules/system/src/Tests/Menu/AssertMenuActiveTrailTrait.php b/core/modules/system/src/Tests/Menu/AssertMenuActiveTrailTrait.php
index 5db3c2c..ecf6f43 100644
--- a/core/modules/system/src/Tests/Menu/AssertMenuActiveTrailTrait.php
+++ b/core/modules/system/src/Tests/Menu/AssertMenuActiveTrailTrait.php
@@ -37,7 +37,7 @@ protected function assertMenuActiveTrail($tree, $last_active) {
         $part_xpath .= 'li[contains(@class, :class)]/a[contains(@href, :href) and contains(text(), :title)]';
         $part_args = array(
           ':class' => 'active-trail',
-          ':href' => Url::fromUri('base:://' . $link_path)->toString(),
+          ':href' => Url::fromUri('base://' . $link_path)->toString(),
           ':title' => $link_title,
         );
         $xpath .= $this->buildXPathQuery($part_xpath, $part_args);
@@ -57,7 +57,7 @@ protected function assertMenuActiveTrail($tree, $last_active) {
     $args = array(
       ':class-trail' => 'active-trail',
       ':class-active' => 'active',
-      ':href' => Url::fromUri('base:://' . $active_link_path)->toString(),
+      ':href' => Url::fromUri('base://' . $active_link_path)->toString(),
       ':title' => $active_link_title,
     );
     $elements = $this->xpath($xpath, $args);
diff --git a/core/modules/system/src/Tests/Menu/BreadcrumbTest.php b/core/modules/system/src/Tests/Menu/BreadcrumbTest.php
index 72d14aa..6e3db53 100644
--- a/core/modules/system/src/Tests/Menu/BreadcrumbTest.php
+++ b/core/modules/system/src/Tests/Menu/BreadcrumbTest.php
@@ -278,7 +278,7 @@ function testBreadCrumbs() {
       // other than the breadcrumb trail.
       $elements = $this->xpath('//nav[@id=:menu]/descendant::a[@href=:href]', array(
         ':menu' => 'block-bartik-tools',
-        ':href' => Url::fromUri('base:://' . $link_path)->toString(),
+        ':href' => Url::fromUri('base://' . $link_path)->toString(),
       ));
       $this->assertTrue(count($elements) == 1, "Link to {$link_path} appears only once.");