diff --git a/core/lib/Drupal/Component/Utility/Url.php b/core/lib/Drupal/Component/Utility/Url.php
index cdc01c8..07d959e 100644
--- a/core/lib/Drupal/Component/Utility/Url.php
+++ b/core/lib/Drupal/Component/Utility/Url.php
@@ -226,6 +226,7 @@ public static function isExternal($path) {
   public static function externalIsLocal($url, $base_url) {
     $url_parts = parse_url($url);
     $base_host = parse_url($base_url, PHP_URL_HOST);
+    $base_url = substr($base_url, strpos($base_url, $base_host) + strlen($base_host));
 
     if (!isset($url_parts['path'])) {
       return ($url_parts['host'] == $base_host);
diff --git a/core/tests/Drupal/Tests/Component/Utility/UrlTest.php b/core/tests/Drupal/Tests/Component/Utility/UrlTest.php
index de62324..b4e0e3e 100644
--- a/core/tests/Drupal/Tests/Component/Utility/UrlTest.php
+++ b/core/tests/Drupal/Tests/Component/Utility/UrlTest.php
@@ -408,4 +408,14 @@ protected function dataEnhanceWithPrefix(array $urls) {
     return $data;
   }
 
+  /**
+   * Test externalIsLocal method.
+   *
+   * @see \Drupal\Component\Utility\Url::externalIsLocal()
+   */
+  public function testExternalIsLocal() {
+    $this->assertTrue(Url::externalIsLocal('http://example.com/url', 'http://example.com/'));
+    $this->assertFalse(Url::externalIsLocal('http://example.com/url', 'http://moexample.com/'));
+  }
+
 }