diff --git a/core/lib/Drupal/Core/StreamWrapper/LocalStream.php b/core/lib/Drupal/Core/StreamWrapper/LocalStream.php
index 99a2b1e..4419419 100644
--- a/core/lib/Drupal/Core/StreamWrapper/LocalStream.php
+++ b/core/lib/Drupal/Core/StreamWrapper/LocalStream.php
@@ -78,9 +78,8 @@ function getUri() {
    * @param string $uri
    *   Optional URI.
    *
-   * @return string|bool
-   *   Returns a string representing a location suitable for writing of a file,
-   *   or FALSE if unable to write to the file such as with read-only streams.
+   * @return string
+   *   Returns a string representing a location suitable for writing of a file.
    *
    * @throws \InvalidArgumentException
    *   If a malformed $uri parameter is passed in.
@@ -308,7 +307,7 @@ public function stream_close() {
    * @param int $cast_as
    *   Can be STREAM_CAST_FOR_SELECT or STREAM_CAST_AS_STREAM.
    *
-   * @return resource|FALSE
+   * @return resource|false
    *   The underlying stream resource or FALSE if stream_select() is not
    *   supported.
    *
diff --git a/core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface.php b/core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface.php
index 3f9f5d4..8fe1d1f 100644
--- a/core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface.php
+++ b/core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface.php
@@ -86,7 +86,7 @@ public function realpath();
    *   An optional URI.
    *
    * @return string
-   *   A string containing the directory name, or FALSE if not applicable.
+   *   A string containing the directory name.
    *
    * @see drupal_dirname()
    */
diff --git a/core/lib/Drupal/Core/StreamWrapper/SystemStream.php b/core/lib/Drupal/Core/StreamWrapper/SystemStream.php
index 5d53458..4460ee6 100644
--- a/core/lib/Drupal/Core/StreamWrapper/SystemStream.php
+++ b/core/lib/Drupal/Core/StreamWrapper/SystemStream.php
@@ -48,9 +48,9 @@ public function getOwnerName($uri = NULL) {
    * {@inheritdoc}
    */
   public function getTarget($uri = NULL) {
-    $target = $this->extractTarget($uri);
-    if (file_exists($this->getDirectoryPath($uri) . '/' . $target)) {
-      return $target;
+    $target = strstr(parent::getTarget($uri), '/') ?: '';
+    if (file_exists($this->getDirectoryPath($uri) . $target)) {
+      return trim($target, '/');
     }
     else {
       throw new \InvalidArgumentException(sprintf('Target %s does not exist', $uri));
@@ -58,27 +58,6 @@ public function getTarget($uri = NULL) {
   }
 
   /**
-   * Returns the local target of the resource, regardless of whether it exists.
-   *
-   * @param string $uri
-   *   Optional URI.
-   *
-   * @return string
-   *   A path to the local target.
-   *
-   * @throws \InvalidArgumentException
-   */
-  protected function extractTarget($uri = NULL) {
-    // If the owner doesn't exist at all, we don't extract anything.
-    if ($this->getOwnerName($uri)) {
-      $target = parent::getTarget($uri);
-      // Remove the preceding owner name including slash from the path.
-      $start = strpos($target, '/');
-      return ($start === FALSE) ? '' : substr($target, $start + 1);
-    }
-  }
-
-  /**
    * Returns a web accessible URL for the resource.
    *
    * This function should return a URL that can be embedded in a web page
@@ -86,6 +65,9 @@ protected function extractTarget($uri = NULL) {
    * "youtube://xIpLd0WQKCY" might be
    * "http://www.youtube.com/watch?v=xIpLd0WQKCY".
    *
+   * @param string $uri
+   *   An optional URI.
+   *
    * @return string
    *   Returns a string containing a web accessible URL for the resource.
    *
@@ -97,8 +79,12 @@ public function getExternalUrl($uri = NULL) {
       throw new \InvalidArgumentException(sprintf('Extension directory for %s does not exist.', $uri));
     }
 
-    $target = $this->extractTarget($uri);
-    $path = $target != '' ? '/' . UrlHelper::encodePath(str_replace('\\', '/', $target)) : '';
+    // Find the path following the owner name.
+    if ($path = strstr(parent::getTarget($uri), '/')) {
+      // Clean the path.
+      $path = rtrim(UrlHelper::encodePath(str_replace('\\', '/', $path)), '/');
+    }
+
     return \Drupal::request()->getUri() . $dir . $path;
   }
 }
diff --git a/core/modules/system/src/Tests/File/SystemStreamUnitTest.php b/core/modules/system/src/Tests/File/SystemStreamUnitTest.php
index be33a14..456ec98 100644
--- a/core/modules/system/src/Tests/File/SystemStreamUnitTest.php
+++ b/core/modules/system/src/Tests/File/SystemStreamUnitTest.php
@@ -404,7 +404,7 @@ private function runTestOnInstanceMethod($instance, $method, array $data) {
         }
       }
       else {
-        $this->assertEqual($instance->$method($uri), $info[0], $info[1]);
+        $this->assertEqual($instance->$method($uri), $info[0]/*, $info[1]*/);
       }
     }
   }