diff --git a/core/tests/Drupal/Tests/Core/PathProcessor/PathProcessorTest.php b/core/tests/Drupal/Tests/Core/PathProcessor/PathProcessorTest.php
index 1134ecc..6412ef8 100644
--- a/core/tests/Drupal/Tests/Core/PathProcessor/PathProcessorTest.php
+++ b/core/tests/Drupal/Tests/Core/PathProcessor/PathProcessorTest.php
@@ -120,6 +120,7 @@ function testProcessInbound() {
         'language.negotiation' => array(
           'url' => array(
             'prefixes' => array('fr' => 'fr'),
+            'source' => LanguageNegotiationUrl::CONFIG_PATH_PREFIX,
           ),
         ),
       )