diff --git a/core/lib/Drupal/Core/Path/AliasStorageInterface.php b/core/lib/Drupal/Core/Path/AliasStorageInterface.php
index 5d22b46..598f986 100644
--- a/core/lib/Drupal/Core/Path/AliasStorageInterface.php
+++ b/core/lib/Drupal/Core/Path/AliasStorageInterface.php
@@ -138,7 +138,7 @@ public function languageAliasExists();
    *   Table header.
    * @param string|null $keys
    *   (optional) Search keyword that may include one or more '*' as a wildcard
-   *   value. Will be converted to lower case.
+   *   value. This will be converted to lower case.
    *
    * @return array
    *   Array of items to be displayed on the current page.
diff --git a/core/lib/Drupal/Core/Routing/RouteBuilder.php b/core/lib/Drupal/Core/Routing/RouteBuilder.php
index 0404cd4..fe90787 100644
--- a/core/lib/Drupal/Core/Routing/RouteBuilder.php
+++ b/core/lib/Drupal/Core/Routing/RouteBuilder.php
@@ -186,14 +186,12 @@ public function rebuild() {
     // static defined ones.
     $this->dispatcher->dispatch(RoutingEvents::DYNAMIC, new RouteBuildEvent($collection));
     // Process the whole collection since we cannot tell what was newly added.
-    $this->processCollection($collection);
+    $this->applyLowerCaseCollection($collection);
 
     // ALTER is the final step to alter all the existing routes. We cannot stop
     // people from adding new routes here, but we define two separate steps to
     // make it clear.
     $this->dispatcher->dispatch(RoutingEvents::ALTER, new RouteBuildEvent($collection));
-    // Process the whole collection again since we cannot tell what was changed.
-    $this->processCollection($collection);
 
     $this->checkProvider->setChecks($collection);
 
@@ -234,9 +232,8 @@ public function destruct() {
    * @param \Symfony\Component\Routing\RouteCollection $collection
    *   A route collection.
    */
-  protected function processCollection(RouteCollection $collection) {
-    /** @var \Symfony\Component\Routing\Route $route */
-    foreach ($collection as $route) {
+  protected function applyLowerCaseCollection(RouteCollection $collection) {
+    foreach ($collection->getAll() as $route) {
       // Force each path to be lower case.
       $path = Unicode::strtolower($route->getPath());
       $route->setPath($path);
diff --git a/core/lib/Drupal/Core/Routing/UrlMatcher.php b/core/lib/Drupal/Core/Routing/UrlMatcher.php
index 0b97f0a..a7a4e75 100644
--- a/core/lib/Drupal/Core/Routing/UrlMatcher.php
+++ b/core/lib/Drupal/Core/Routing/UrlMatcher.php
@@ -49,23 +49,23 @@ public function finalMatch(RouteCollection $collection, Request $request) {
   /**
    * Tries to match a URL with a set of routes.
    *
-   * This version differe from the Symfony parent version in two respects.
+   * This version differs from the Symfony parent version in two respects.
    * First, the $pathinfo string is converted to lower case. In addition, we
    * remove the check against any static prefix since we would already have
    * matched the static prefix in \Drupal\Core\Routing\RouteProvider before
    * arriving here.
    *
    * @param string $pathinfo
-   *   The path info to be parsed
+   *   The path info to be parsed.
    * @param RouteCollection $routes
-   *   The set of routes
+   *   The set of routes.
    *
    * @return array An array of parameters
    *
    * @throws \Symfony\Component\Routing\Exception\ResourceNotFoundException
-   *   If the resource could not be found
+   *   If the resource could not be found.
    * @throws \Symfony\Component\Routing\Exception\MethodNotAllowedException
-   *   If the resource was found but the request method is not allowed
+   *   If the resource was found but the request method is not allowed.
    */
   protected function matchCollection($pathinfo, RouteCollection $routes)
   {