diff --git a/core/lib/Drupal/Core/DependencyInjection/Compiler/TaggedHandlersPass.php b/core/lib/Drupal/Core/DependencyInjection/Compiler/TaggedHandlersPass.php
index 43e10ef..e550f0b 100644
--- a/core/lib/Drupal/Core/DependencyInjection/Compiler/TaggedHandlersPass.php
+++ b/core/lib/Drupal/Core/DependencyInjection/Compiler/TaggedHandlersPass.php
@@ -86,12 +86,11 @@ public function process(ContainerBuilder $container) {
         $method = new \ReflectionMethod($consumer->getClass(), $method_name);
         $params = $method->getParameters();
 
-        $interface_pos = NULL;
+        $interface_pos = 0;
         $id_pos = NULL;
         $priority_pos = NULL;
         foreach ($params as $pos => $param) {
           if ($param->getClass()) {
-            $interface_pos = $pos;
             $interface = $param->getClass();
           }
           if ($param->getName() == 'id') {
diff --git a/core/lib/Drupal/Core/ParamConverter/ParamConverterManager.php b/core/lib/Drupal/Core/ParamConverter/ParamConverterManager.php
index 0cc7289..cfc8963 100644
--- a/core/lib/Drupal/Core/ParamConverter/ParamConverterManager.php
+++ b/core/lib/Drupal/Core/ParamConverter/ParamConverterManager.php
@@ -31,7 +31,7 @@ class ParamConverterManager implements ParamConverterManagerInterface {
   /**
    * {@inheritdoc}
    */
-  public function addConverter($id, ParamConverterInterface $param_converter, $priority = 0) {
+  public function addConverter(ParamConverterInterface $param_converter, $id) {
     $this->converters[$id] = $param_converter;
     return $this;
   }
diff --git a/core/lib/Drupal/Core/ParamConverter/ParamConverterManagerInterface.php b/core/lib/Drupal/Core/ParamConverter/ParamConverterManagerInterface.php
index d2c0e02..a1761da 100644
--- a/core/lib/Drupal/Core/ParamConverter/ParamConverterManagerInterface.php
+++ b/core/lib/Drupal/Core/ParamConverter/ParamConverterManagerInterface.php
@@ -18,16 +18,14 @@
   /**
    * Registers a parameter converter with the manager.
    *
-   * @param string $id
-   *   The parameter converter service id to register.
    * @param \Drupal\Core\ParamConverter\ParamConverterInterface $param_converter
    *   The added param converter instance.
-   * @param int $priority
-   *   (optional) The priority of the converter. Defaults to 0.
+   * @param string $id
+   *   The parameter converter service id to register.
    *
    * @return $this
    */
-  public function addConverter($id, ParamConverterInterface $param_converter, $priority = 0);
+  public function addConverter(ParamConverterInterface $param_converter, $id);
 
   /**
    * Lazy-loads converter services.
diff --git a/core/tests/Drupal/Tests/Core/DependencyInjection/Compiler/TaggedHandlersPassTest.php b/core/tests/Drupal/Tests/Core/DependencyInjection/Compiler/TaggedHandlersPassTest.php
index 792d121..2d62eab 100644
--- a/core/tests/Drupal/Tests/Core/DependencyInjection/Compiler/TaggedHandlersPassTest.php
+++ b/core/tests/Drupal/Tests/Core/DependencyInjection/Compiler/TaggedHandlersPassTest.php
@@ -207,11 +207,11 @@ public function testProcessWithIdParameter() {
 
     $method_calls = $container->getDefinition('consumer_id')->getMethodCalls();
     $this->assertCount(2, $method_calls);
-    $this->assertEquals('handler2', $method_calls[0][1][0]);
-    $this->assertEquals(new Reference('handler2'), $method_calls[0][1][1]);
+    $this->assertEquals(new Reference('handler2'), $method_calls[0][1][0]);
+    $this->assertEquals('handler2', $method_calls[0][1][1]);
     $this->assertEquals(10, $method_calls[0][1][2]);
-    $this->assertEquals('handler1', $method_calls[1][1][0]);
-    $this->assertEquals(new Reference('handler1'), $method_calls[1][1][1]);
+    $this->assertEquals(new Reference('handler1'), $method_calls[1][1][0]);
+    $this->assertEquals('handler1', $method_calls[1][1][1]);
     $this->assertEquals(0, $method_calls[1][1][2]);
   }
 
@@ -278,7 +278,7 @@ public function addHandler(HandlerInterface $instance, $priority = 0) {
   }
   public function addNoPriority(HandlerInterface $instance) {
   }
-  public function addWithId($id, HandlerInterface $instance, $priority = 0) {
+  public function addWithId(HandlerInterface $instance, $id, $priority = 0) {
   }
 }
 class InvalidConsumer {
diff --git a/core/tests/Drupal/Tests/Core/ParamConverter/ParamConverterManagerTest.php b/core/tests/Drupal/Tests/Core/ParamConverter/ParamConverterManagerTest.php
index 69d2b05..d308a5d 100644
--- a/core/tests/Drupal/Tests/Core/ParamConverter/ParamConverterManagerTest.php
+++ b/core/tests/Drupal/Tests/Core/ParamConverter/ParamConverterManagerTest.php
@@ -53,12 +53,12 @@ public function setUp() {
    *
    * @covers ::getConverter()
    */
-  public function testGetConverter($name, $priority, $class) {
+  public function testGetConverter($name, $class) {
     $converter = $this->getMockBuilder('Drupal\Core\ParamConverter\ParamConverterInterface')
       ->setMockClassName($class)
       ->getMock();
 
-    $this->manager->addConverter($name, $converter, $priority);
+    $this->manager->addConverter($converter, $name);
 
     $this->assertInstanceOf($class, $this->manager->getConverter($name));
     // Assert that a second call to getConverter() does not use the container.
@@ -87,13 +87,13 @@ public function testGetConverterException() {
    */
   public function providerTestAddConverter() {
     $converters[0]['unsorted'] = array(
-      array('name' => 'raspberry', 'priority' => 10),
-      array('name' => 'pear', 'priority' => 5),
-      array('name' => 'strawberry', 'priority' => 20),
-      array('name' => 'pineapple', 'priority' => 0),
-      array('name' => 'banana', 'priority' => -10),
-      array('name' => 'apple', 'priority' => -10),
-      array('name' => 'peach', 'priority' => 5),
+      array('name' => 'strawberry'),
+      array('name' => 'raspberry'),
+      array('name' => 'pear'),
+      array('name' => 'peach'),
+      array('name' => 'pineapple'),
+      array('name' => 'banana'),
+      array('name' => 'apple'),
     );
 
     $converters[0]['sorted'] = array(
@@ -102,13 +102,13 @@ public function providerTestAddConverter() {
     );
 
     $converters[1]['unsorted'] = array(
-      array('name' => 'ape', 'priority' => 0),
-      array('name' => 'cat', 'priority' => -5),
-      array('name' => 'puppy', 'priority' => -10),
-      array('name' => 'llama', 'priority' => -15),
-      array('name' => 'giraffe', 'priority' => 10),
-      array('name' => 'zebra', 'priority' => 10),
-      array('name' => 'eagle', 'priority' => 5),
+      array('name' => 'giraffe'),
+      array('name' => 'zebra'),
+      array('name' => 'eagle'),
+      array('name' => 'ape'),
+      array('name' => 'cat'),
+      array('name' => 'puppy'),
+      array('name' => 'llama'),
     );
 
     $converters[1]['sorted'] = array(
@@ -130,13 +130,13 @@ public function providerTestAddConverter() {
    */
   public function providerTestGetConverter() {
     return array(
-      array('ape', 0, 'ApeConverterClass'),
-      array('cat', -5, 'CatConverterClass'),
-      array('puppy', -10, 'PuppyConverterClass'),
-      array('llama', -15, 'LlamaConverterClass'),
-      array('giraffe', 10, 'GiraffeConverterClass'),
-      array('zebra', 10, 'ZebraConverterClass'),
-      array('eagle', 5, 'EagleConverterClass'),
+      array('ape', 'ApeConverterClass'),
+      array('cat', 'CatConverterClass'),
+      array('puppy', 'PuppyConverterClass'),
+      array('llama', 'LlamaConverterClass'),
+      array('giraffe', 'GiraffeConverterClass'),
+      array('zebra', 'ZebraConverterClass'),
+      array('eagle', 'EagleConverterClass'),
     );
   }
 
@@ -151,7 +151,7 @@ public function testSetRouteParameterConverters($path, $parameters = NULL, $expe
       ->method('applies')
       ->with($this->anything(), 'id', $this->anything())
       ->will($this->returnValue(TRUE));
-    $this->manager->addConverter('applied', $converter);
+    $this->manager->addConverter($converter, 'applied');
 
     $route = new Route($path);
     if ($parameters) {
@@ -213,7 +213,7 @@ public function testConvert() {
       ->method('convert')
       ->with(1, $this->isType('array'), 'id', $this->isType('array'), $this->isInstanceOf('Symfony\Component\HttpFoundation\Request'))
       ->will($this->returnValue('something_better!'));
-    $this->manager->addConverter('test_convert', $converter);
+    $this->manager->addConverter($converter, 'test_convert');
 
     $result = $this->manager->convert($defaults, new Request());
 
@@ -262,7 +262,7 @@ public function testConvertMissingParam() {
       ->method('convert')
       ->with(1, $this->isType('array'), 'id', $this->isType('array'), $this->isInstanceOf('Symfony\Component\HttpFoundation\Request'))
       ->will($this->returnValue(NULL));
-    $this->manager->addConverter('test_convert', $converter);
+    $this->manager->addConverter($converter, 'test_convert');
 
     $this->manager->convert($defaults, new Request());
   }