diff --git a/core/lib/Drupal/Core/Controller/ControllerResolver.php b/core/lib/Drupal/Core/Controller/ControllerResolver.php
index 1733738..9ae9788 100644
--- a/core/lib/Drupal/Core/Controller/ControllerResolver.php
+++ b/core/lib/Drupal/Core/Controller/ControllerResolver.php
@@ -107,10 +107,10 @@ protected function doGetArguments(Request $request, $controller, array $paramete
 
     // The parameter converter overrides the raw request attributes with the
     // upcasted objects. However, it keeps a backup copy of the original, raw
-    // values in a special request attribute (':raw'). If a controller argument
+    // values in a special request attribute ('_raw'). If a controller argument
     // has a type hint, we pass it the upcasted object, otherwise we pass it
     // the original, raw value.
-    if ($request->attributes->has(':raw') && $raw = $request->attributes->get(':raw')->all()) {
+    if ($request->attributes->has('_raw') && $raw = $request->attributes->get('_raw')->all()) {
       foreach ($parameters as $parameter) {
         // Use the raw value if a parameter has no typehint.
         if (!$parameter->getClass() && isset($raw[$parameter->name])) {
diff --git a/core/lib/Drupal/Core/ParamConverter/ParamConverterManager.php b/core/lib/Drupal/Core/ParamConverter/ParamConverterManager.php
index a75b138..1237c77 100644
--- a/core/lib/Drupal/Core/ParamConverter/ParamConverterManager.php
+++ b/core/lib/Drupal/Core/ParamConverter/ParamConverterManager.php
@@ -82,7 +82,7 @@ public function enhance(array $defaults, Request $request) {
     }
 
     // Add the copy the raw values of all the URI variables to $defaults.
-    $defaults[':raw'] = $raw;
+    $defaults['_raw'] = $raw;
 
     // Check if all upcasting yielded a result.
     // If an upcast value is NULL do a 404.
diff --git a/core/tests/Drupal/Tests/Core/Controller/ControllerResolverTest.php b/core/tests/Drupal/Tests/Core/Controller/ControllerResolverTest.php
index a1db7e8..4633076 100644
--- a/core/tests/Drupal/Tests/Core/Controller/ControllerResolverTest.php
+++ b/core/tests/Drupal/Tests/Core/Controller/ControllerResolverTest.php
@@ -65,7 +65,7 @@ public function testGetArguments() {
     $request = new \Symfony\Component\HttpFoundation\Request(array(), array(), array(
       'entity' => $mock_entity,
       'user' => $mock_account,
-      ':raw' => new ParameterBag(array('entity' => 1, 'user' => 1)),
+      '_raw' => new ParameterBag(array('entity' => 1, 'user' => 1)),
     ));
     $arguments = $this->controllerResolver->getArguments($request, $controller);