diff --git a/core/core.services.yml b/core/core.services.yml
index 2ae5157..1de7bcb 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -510,7 +510,7 @@ services:
     class: Drupal\Core\Routing\CachedUrlGenerator
     arguments: ['@url_generator.uncached', '@cache.url_generator', '@language_manager', '@router.route_provider']
     calls:
-      - [fromRequestStack, ['@request_stack']]
+      - [prepareCache, ['@request_stack']]
     tags:
       - { name: needs_destruction }
   unrouted_url_assembler:
diff --git a/core/lib/Drupal/Core/Routing/CachedUrlGenerator.php b/core/lib/Drupal/Core/Routing/CachedUrlGenerator.php
index d42b400..7a75a7e 100644
--- a/core/lib/Drupal/Core/Routing/CachedUrlGenerator.php
+++ b/core/lib/Drupal/Core/Routing/CachedUrlGenerator.php
@@ -189,9 +189,15 @@ protected function getRoute($name) {
   }
 
   /**
-   * {@inheritdoc}
+   * Based on the current request load the appropiate set of cached URLs.
+   *
+   * Any cache key algorithm must be sensitive the the case of the URL.
+   * For example '/MY/PAGE' and '/my/page' maybe routed to different controllers
+   * and so different caches may needed at this point.
+   *
+   * @param \Symfony\Component\HttpFoundation\RequestStack $requestStack
    */
-  public function fromRequestStack(RequestStack $requestStack) {
+  public function prepareCache(RequestStack $requestStack) {
     $this->cacheKey = $requestStack->getCurrentRequest()->attributes->get('_system_path');
     if (!RequestHelper::isCleanUrl($requestStack->getCurrentRequest())){
       $this->cacheKey .= '::' . $requestStack->getCurrentRequest()->getScriptName();
@@ -201,7 +207,8 @@ public function fromRequestStack(RequestStack $requestStack) {
       $this->cacheKey .= '::' . $this->languageManager->getCurrentLanguage(Language::TYPE_URL)->getId();
     }
 
-    $this->cacheKey = sha1($this->cacheKey);
+    // Make cacheKeys sensitive to the case of the incomming URL.
+    $this->cacheKey = hash('md4', $this->cacheKey);
 
     $cached = $this->cache->get($this->cacheKey);
     if ($cached) {