diff --git a/core/lib/Drupal/Core/Routing/RouteBuilder.php b/core/lib/Drupal/Core/Routing/RouteBuilder.php
index 3ee3aa1..bc0650d 100644
--- a/core/lib/Drupal/Core/Routing/RouteBuilder.php
+++ b/core/lib/Drupal/Core/Routing/RouteBuilder.php
@@ -80,6 +80,9 @@ public function __construct(MatcherDumperInterface $dumper, LockBackendInterface
 
   /**
    * Rebuilds the route info and dumps to dumper.
+   *
+   * @return bool
+   *   Returns TRUE if the rebuild succeeds, otherwise FALSE.
    */
   public function rebuild() {
     if (!$this->lock->acquire('router_rebuild')) {
@@ -87,7 +90,7 @@ public function rebuild() {
       // We choose to block here since otherwise the routes might not be
       // available, resulting in a 404.
       $this->lock->wait('router_rebuild');
-      return;
+      return FALSE;
     }
 
     $yaml_discovery = $this->getYamlDiscovery();
@@ -119,6 +122,7 @@ public function rebuild() {
     $this->dumper->dump(array('route_set' => 'dynamic_routes'));
 
     $this->lock->release('router_rebuild');
+    return TRUE;
   }
 
   /**
diff --git a/core/tests/Drupal/Tests/Core/Routing/RouteBuilderTest.php b/core/tests/Drupal/Tests/Core/Routing/RouteBuilderTest.php
index 572a99e..7da52c0 100644
--- a/core/tests/Drupal/Tests/Core/Routing/RouteBuilderTest.php
+++ b/core/tests/Drupal/Tests/Core/Routing/RouteBuilderTest.php
@@ -106,7 +106,7 @@ public function testRebuildLockingUnlocking() {
       ->method('findAll')
       ->will($this->returnValue(array()));
 
-    $this->assertNull($this->routeBuilder->rebuild());
+    $this->assertTrue($this->routeBuilder->rebuild());
   }
 
   /**
@@ -128,7 +128,7 @@ public function testRebuildBlockingLock() {
     $this->yamlDiscovery->expects($this->never())
       ->method('findAll');
 
-    $this->assertNull($this->routeBuilder->rebuild());
+    $this->assertFalse($this->routeBuilder->rebuild());
   }
 
   /**
@@ -181,7 +181,7 @@ public function testRebuildWithStaticModuleRoutes() {
       ->with(array('route_set' => 'dynamic_routes'));
 
 
-    $this->routeBuilder->rebuild();
+    $this->assertTrue($this->routeBuilder->rebuild());
   }
 
   /**
@@ -220,7 +220,7 @@ public function testRebuildWithDynamicRoutes() {
       ->method('dump')
       ->with(array('route_set' => 'dynamic_routes'));
 
-    $this->routeBuilder->rebuild();
+    $this->assertTrue($this->routeBuilder->rebuild());
   }
 
 }