diff --git a/core/lib/Drupal/Core/Url.php b/core/lib/Drupal/Core/Url.php
index 123cc7a..5fc1c31 100644
--- a/core/lib/Drupal/Core/Url.php
+++ b/core/lib/Drupal/Core/Url.php
@@ -196,11 +196,19 @@ public static function routed($route_name, $route_parameters = array(), $options
    * @return \Drupal\Core\Url
    *   A new Url object for an unrouted (non-Drupal) URL.
    *
+   * @throws \InvalidArgumentException
+   *   Thrown when the passed in path has no schema.
+   *
    * @see static::routed()
    */
   public static function unrouted($uri, $options = array()) {
+    if (!parse_url($uri, PHP_URL_SCHEME)) {
+      throw new \InvalidArgumentException('You must use a valid URI scheme.  Use base:// for a path e.g. to a Drupal file that needs the base path.');
+    }
+
     $url = new static($uri, array(), $options);
     $url->setUnrouted();
+
     return $url;
   }
 
diff --git a/core/lib/Drupal/Core/Utility/UnroutedUrlAssemblerInterface.php b/core/lib/Drupal/Core/Utility/UnroutedUrlAssemblerInterface.php
index 36fca11..f72d876 100644
--- a/core/lib/Drupal/Core/Utility/UnroutedUrlAssemblerInterface.php
+++ b/core/lib/Drupal/Core/Utility/UnroutedUrlAssemblerInterface.php
@@ -49,6 +49,9 @@
    *
    * @return
    *   A string containing a relative or absolute URL.
+   *
+   * @throws \InvalidArgumentException
+   *   Thrown when the passed in path has no schema.
    */
   public function assemble($uri, array $options = array());
 
diff --git a/core/tests/Drupal/Tests/Core/UnroutedUrlTest.php b/core/tests/Drupal/Tests/Core/UnroutedUrlTest.php
index 472dc64..317ad62 100644
--- a/core/tests/Drupal/Tests/Core/UnroutedUrlTest.php
+++ b/core/tests/Drupal/Tests/Core/UnroutedUrlTest.php
@@ -104,6 +104,17 @@ public function testCreateFromRequest() {
   }
 
   /**
+   * Tests the unrouted method with an non-scheme path.
+   *
+   * @covers ::unrouted()
+   *
+   * @expectedException \InvalidArgumentException
+   */
+  public function testUnroutedWithNonScheme() {
+    Url::unrouted('test');
+  }
+
+  /**
    * Tests the isExternal() method.
    *
    * @depends testCreateFromPath