diff --git a/src/Symfony/Bundle/FrameworkBundle/Controller/ControllerNameParser.php b/src/Symfony/Bundle/FrameworkBundle/Controller/ControllerNameParser.php
index 374d0eba10..989dc8cd23 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Controller/ControllerNameParser.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Controller/ControllerNameParser.php
@@ -46,11 +46,12 @@ class ControllerNameParser
      */
     public function parse($controller)
     {
-        $originalController = $controller;
-        if (3 !== count($parts = explode(':', $controller))) {
+        $parts = explode(':', $controller);
+        if (3 !== count($parts) || in_array('', $parts, true)) {
             throw new \InvalidArgumentException(sprintf('The "%s" controller is not a valid "a:b:c" controller string.', $controller));
         }
 
+        $originalController = $controller;
         list($bundle, $controller, $action) = $parts;
         $controller = str_replace('/', '\\', $controller);
         $bundles = array();
diff --git a/src/Symfony/Bundle/FrameworkBundle/Routing/DelegatingLoader.php b/src/Symfony/Bundle/FrameworkBundle/Routing/DelegatingLoader.php
index 801149372a..29f3072a89 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Routing/DelegatingLoader.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Routing/DelegatingLoader.php
@@ -21,7 +21,7 @@ use Psr\Log\LoggerInterface;
  * DelegatingLoader delegates route loading to other loaders using a loader resolver.
  *
  * This implementation resolves the _controller attribute from the short notation
- * to the fully-qualified form (from a:b:c to class:method).
+ * to the fully-qualified form (from a:b:c to class::method).
  *
  * @author Fabien Potencier <fabien@symfony.com>
  */
@@ -85,15 +85,17 @@ class DelegatingLoader extends BaseDelegatingLoader
         $this->loading = false;
 
         foreach ($collection->all() as $route) {
-            if ($controller = $route->getDefault('_controller')) {
-                try {
-                    $controller = $this->parser->parse($controller);
-                } catch (\InvalidArgumentException $e) {
-                    // unable to optimize unknown notation
-                }
-
-                $route->setDefault('_controller', $controller);
+            if (!$controller = $route->getDefault('_controller')) {
+                continue;
             }
+
+            try {
+                $controller = $this->parser->parse($controller);
+            } catch (\InvalidArgumentException $e) {
+                // unable to optimize unknown notation
+            }
+
+            $route->setDefault('_controller', $controller);
         }
 
         return $collection;