diff --git a/core/lib/Drupal/Core/Entity/EntityResolverManager.php b/core/lib/Drupal/Core/Entity/EntityResolverManager.php
index 9a2bde2..2531b7d 100644
--- a/core/lib/Drupal/Core/Entity/EntityResolverManager.php
+++ b/core/lib/Drupal/Core/Entity/EntityResolverManager.php
@@ -150,6 +150,18 @@ protected function setParametersFromEntityInformation(Route $route) {
     }
     if (isset($entity_type) && $this->entityManager->getDefinition($entity_type)) {
       $parameter_definitions = $route->getOption('parameters') ?: array();
+
+      // First try to figure out whether there is already a parameter upcasting
+      // the same entity type already.
+      foreach ($parameter_definitions as $info) {
+        if (isset($info['type'])) {
+          list(, $parameter_entity_type) = explode(':', $info['type']);
+          if ($parameter_entity_type == $entity_type) {
+            return;
+          }
+        }
+      }
+
       if (!isset($parameter_definitions[$entity_type])) {
         $parameter_definitions[$entity_type] = array();
       }
diff --git a/core/modules/node/lib/Drupal/node/Access/NodeAddAccessCheck.php b/core/modules/node/lib/Drupal/node/Access/NodeAddAccessCheck.php
index 8d72223..451b066 100644
--- a/core/modules/node/lib/Drupal/node/Access/NodeAddAccessCheck.php
+++ b/core/modules/node/lib/Drupal/node/Access/NodeAddAccessCheck.php
@@ -10,6 +10,7 @@
 use Drupal\Core\Entity\EntityManagerInterface;
 use Drupal\Core\Routing\Access\AccessInterface;
 use Drupal\Core\Session\AccountInterface;
+use Drupal\node\NodeTypeInterface;
 use Symfony\Component\Routing\Route;
 use Symfony\Component\HttpFoundation\Request;
 
@@ -41,8 +42,8 @@ public function __construct(EntityManagerInterface $entity_manager) {
   public function access(Route $route, Request $request, AccountInterface $account) {
     $access_controller = $this->entityManager->getAccessController('node');
     // If a node type is set on the request, just check that.
-    if ($request->attributes->has('node_type')) {
-      return $access_controller->createAccess($request->attributes->get('node_type')->type, $account) ? static::ALLOW : static::DENY;
+    if (($node_type = $request->attributes->get('node_type')) && $node_type instanceof NodeTypeInterface) {
+      return $access_controller->createAccess($node_type->type, $account) ? static::ALLOW : static::DENY;
     }
     foreach (node_permissions_get_configured_types() as $type) {
       if ($access_controller->createAccess($type->type, $account)) {
diff --git a/core/tests/Drupal/Tests/Core/Entity/EntityResolverManagerTest.php b/core/tests/Drupal/Tests/Core/Entity/EntityResolverManagerTest.php
index 6eba381..0909220 100644
--- a/core/tests/Drupal/Tests/Core/Entity/EntityResolverManagerTest.php
+++ b/core/tests/Drupal/Tests/Core/Entity/EntityResolverManagerTest.php
@@ -221,6 +221,37 @@ public function testSetRouteOptionsWithEntityFormNoUpcasting() {
     $this->assertEmpty($route->getOption('parameters'));
   }
 
+  /**
+   * Tests the setRouteOptions method with an _entity_view route.
+   *
+   * @covers ::setRouteOptions()
+   * @covers ::getController()
+   * @covers ::getEntityTypes()
+   * @covers ::setParametersFromReflection()
+   * @covers ::setParametersFromEntityInformation()
+   */
+  public function testSetRouteOptionsWithEntityViewRouteAndManualParameters() {
+    $this->setupEntityTypes();
+    $route = new Route('/example/{foo}',
+      array(
+        '_entity_view' => 'entity_test.view',
+      ),
+      array(),
+      array(
+        'parameters' => array(
+          'foo' => array(
+            'type' => 'entity:entity_test',
+          ),
+        ),
+      )
+    );
+
+    $defaults = $route->getDefaults();
+    $this->entityResolverManager->setRouteOptions($route);
+    $this->assertEquals($defaults, $route->getDefaults());
+    $parameters = $route->getOption('parameters');
+    $this->assertEquals(array('foo' => array('type' => 'entity:entity_test')), $parameters);
+  }
 
   /**
    * Tests the setRouteOptions method with an _entity_view route.