diff --git a/core/lib/Drupal/Core/Controller/TitleResolver.php b/core/lib/Drupal/Core/Controller/TitleResolver.php
index a418661..5b9103a 100644
--- a/core/lib/Drupal/Core/Controller/TitleResolver.php
+++ b/core/lib/Drupal/Core/Controller/TitleResolver.php
@@ -44,29 +44,31 @@ public function __construct(ControllerResolverInterface $controller_resolver, Tr
   }
 
   /**
-   * Returns the title from a static or dynamic title.
+   * Returns the title from a static or dynamic title for the route.
    *
    * @param \Symfony\Component\HttpFoundation\Request $request
    *   The request object passed to the title callback.
    * @param \Symfony\Component\Routing\Route $route
    *   The route information of the route to fetch the title.
    *
-   * @return string
-   *   The title of the route as string.
+   * @return string|NULL
+   *   The title for the route.
    */
   public function getTitle(Request $request, Route $route) {
-    // A dynamic title takes priority.
-    if ($route->hasDefault('_title_callback')) {
-      $callback = $route->getDefault('_title_callback');
+    $route_title = NULL;
+    // A dynamic title takes priority. Route::getDefault() returns NULL if the
+    // named default is not set.  By testing thevalue directly, we also
+    // avoid trying to use empty values.
+    if ($callback = $route->getDefault('_title_callback')) {
       $callable = $this->controllerResolver->getControllerFromDefinition($callback);
       $arguments = $this->controllerResolver->getArguments($request, $callable);
-      return call_user_func_array($callable, $arguments);
+      $route_title = call_user_func_array($callable, $arguments);
     }
-    elseif ($route->hasDefault('_title')) {
+    elseif ($title = $route->getDefault('_title')) {
       // Fall back to a static string from the route.
-      $title = $route->getDefault('_title');
-      return $this->t($title);
+      $route_title = $this->t($title);
     }
+    return $route_title;
   }
 
   /**