diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index ac5968b..11e9743 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -428,7 +428,8 @@ function drupal_settings_initialize() {
   Site::init(DRUPAL_ROOT, isset($sites) ? $sites : NULL, isset($conf_path) ? $conf_path : NULL);
 
   // Make $conf_path available as local variable in settings.php.
-  $conf_path = Site::getSitePath();
+  // Concatenation is safe here, since $conf_path is known to be not empty.
+  $conf_path = Site::getPath();
   if ($conf_path !== '' && is_readable(DRUPAL_ROOT . '/' . $conf_path . '/settings.php')) {
     include_once DRUPAL_ROOT . '/' . $conf_path . '/settings.php';
   }
diff --git a/core/lib/Drupal/Core/Utility/Site.php b/core/lib/Drupal/Core/Utility/Site.php
index d0f0f39..aadb5a1 100644
--- a/core/lib/Drupal/Core/Utility/Site.php
+++ b/core/lib/Drupal/Core/Utility/Site.php
@@ -57,14 +57,12 @@ class Site {
    *   potential value from the root /settings.php file.
    */
   public static function init($root_directory, array $sites = NULL, $custom_path = NULL) {
-    if (isset(self::$instance)) {
-      if (!self::$instance->isInstaller) {
-        throw new \BadMethodCallException('Site path is initialized already.');
-      }
-    }
-    else {
+    if (!isset(self::$instance)) {
       new self($root_directory);
     }
+    elseif (!self::$instance->isInstaller) {
+      throw new \BadMethodCallException('Site path is initialized already.');
+    }
     self::$instance->initializePath($sites, $custom_path);
     return self::$instance;
   }
@@ -257,15 +255,6 @@ private function getSimpletestPath() {
   }
 
   /**
-   * Returns the relative path of the site directory, if any.
-   *
-   * @return string
-   */
-  public static function getSitePath() {
-    return self::$instance->path;
-  }
-
-  /**
    * Prefixes a given filepath with the site directory, if any.
    *
    * @param string $filepath
@@ -301,6 +290,8 @@ private function resolvePath($filepath) {
    *
    * @return string
    *   The given $filepath, potentially prefixed with the site path.
+   *
+   * @see \Drupal\Core\Utility\Site::getAbsolutePath()
    */
   public static function getPath($filepath = '') {
     return self::$instance->resolvePath($filepath);
@@ -315,9 +306,17 @@ public static function getPath($filepath = '') {
    * @return string
    *   The given $filepath, potentially prefixed with the site path, as an
    *   absolute filesystem path.
+   *
+   * @see \Drupal\Core\Utility\Site::getPath()
    */
   public static function getAbsolutePath($filepath = '') {
-    return self::$instance->root . '/' . self::$instance->resolvePath($filepath);
+    $filepath = self::$instance->resolvePath($filepath);
+    if ($filepath !== '') {
+      return self::$instance->root . '/' . $filepath;
+    }
+    else {
+      return self::$instance->root;
+    }
   }
 
   /**