diff --git a/core/lib/Drupal/Core/Path/AliasStorage.php b/core/lib/Drupal/Core/Path/AliasStorage.php
index bd027c8..72663c2 100644
--- a/core/lib/Drupal/Core/Path/AliasStorage.php
+++ b/core/lib/Drupal/Core/Path/AliasStorage.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\Core\Path;
 
+use Drupal\Component\Utility\Unicode;
 use Drupal\Core\Database\Connection;
 use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\Language\LanguageInterface;
@@ -50,7 +51,7 @@ public function save($source, $alias, $langcode = LanguageInterface::LANGCODE_NO
 
     $fields = array(
       'source' => $source,
-      'alias' => $alias,
+      'alias' => Unicode::strtolower($alias),
       'langcode' => $langcode,
     );
 
diff --git a/core/lib/Drupal/Core/PathProcessor/PathProcessorAlias.php b/core/lib/Drupal/Core/PathProcessor/PathProcessorAlias.php
index 206e566..07e3a38 100644
--- a/core/lib/Drupal/Core/PathProcessor/PathProcessorAlias.php
+++ b/core/lib/Drupal/Core/PathProcessor/PathProcessorAlias.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\Core\PathProcessor;
 
+use Drupal\Component\Utility\Unicode;
 use Drupal\Core\Cache\CacheableMetadata;
 use Drupal\Core\Path\AliasManagerInterface;
 use Symfony\Component\HttpFoundation\Request;
@@ -37,8 +38,8 @@ public function __construct(AliasManagerInterface $alias_manager) {
    * Implements Drupal\Core\PathProcessor\InboundPathProcessorInterface::processInbound().
    */
   public function processInbound($path, Request $request) {
-    $path = $this->aliasManager->getPathByAlias($path);
-    return $path;
+    $path = Unicode::strtolower($path);
+    return $this->aliasManager->getPathByAlias($path);
   }
 
   /**