diff --git a/core/lib/Drupal/Core/Template/TwigExtension.php b/core/lib/Drupal/Core/Template/TwigExtension.php
index 0c1ee37..29b5669 100644
--- a/core/lib/Drupal/Core/Template/TwigExtension.php
+++ b/core/lib/Drupal/Core/Template/TwigExtension.php
@@ -77,6 +77,7 @@ public function getFunctions() {
       new \Twig_SimpleFunction('url_from_path', array($this, 'getUrlFromPath'), array('is_safe_callback' => array($this, 'isUrlGenerationSafe'))),
       new \Twig_SimpleFunction('link', array($this, 'getLink')),
       new \Twig_SimpleFunction('file_url', 'file_create_url'),
+      new \Twig_SimpleFunction('active_theme_path', 'activeThemePath'),
     );
   }
 
@@ -217,6 +218,16 @@ public function getLink($text, $url) {
   }
 
   /**
+   * Gets the path of the active theme.
+   *
+   * @return string
+   *   The path to the active theme.
+   */
+  public function activeThemePath() {
+    return \Drupal::service('theme.manager')->getActiveTheme()->getPath();
+  }
+
+  /**
    * Determines at compile time whether the generated URL will be safe.
    *
    * Saves the unneeded automatic escaping for performance reasons.