diff --git a/core/lib/Drupal/Core/DependencyInjection/Compiler/TaggedHandlersPass.php b/core/lib/Drupal/Core/DependencyInjection/Compiler/TaggedHandlersPass.php
index 04b56aa44c3a30baa0b5e22be24f050c1e97073f..3386e6af6bd731586e0e52e280a2ad2d0c1f2b12 100644
--- a/core/lib/Drupal/Core/DependencyInjection/Compiler/TaggedHandlersPass.php
+++ b/core/lib/Drupal/Core/DependencyInjection/Compiler/TaggedHandlersPass.php
@@ -77,6 +77,7 @@ class TaggedHandlersPass implements CompilerPassInterface {
   public function process(ContainerBuilder $container) {
     foreach ($container->findTaggedServiceIds('service_collector') as $consumer_id => $passes) {
       foreach ($passes as $pass) {
+        $interface = NULL;
         $tag = isset($pass['tag']) ? $pass['tag'] : $consumer_id;
         $method_name = isset($pass['call']) ? $pass['call'] : 'addHandler';
         $required = isset($pass['required']) ? $pass['required'] : FALSE;
diff --git a/core/tests/Drupal/Tests/Core/DependencyInjection/Compiler/TaggedHandlersPassTest.php b/core/tests/Drupal/Tests/Core/DependencyInjection/Compiler/TaggedHandlersPassTest.php
index 2eeb603b4c7774c118d624161efb65185e434882..6719cbc96fcc2d8b5bb99ca76f7aba770487455a 100644
--- a/core/tests/Drupal/Tests/Core/DependencyInjection/Compiler/TaggedHandlersPassTest.php
+++ b/core/tests/Drupal/Tests/Core/DependencyInjection/Compiler/TaggedHandlersPassTest.php
@@ -64,13 +64,16 @@ public function testProcessRequiredHandlers() {
    * Tests consumer with missing interface in non-production environment.
    *
    * @expectedException \Symfony\Component\DependencyInjection\Exception\LogicException
-   * @expectedExceptionMessage Service consumer 'consumer_id' class method Drupal\Tests\Core\DependencyInjection\Compiler\InvalidConsumer::addHandler() has to type-hint an interface.
+   * @expectedExceptionMessage Service consumer 'consumer_id1' class method Drupal\Tests\Core\DependencyInjection\Compiler\InvalidConsumer::addHandler() has to type-hint an interface.
    * @covers ::process
    */
   public function testProcessMissingInterface() {
     $container = $this->buildContainer();
     $container
-      ->register('consumer_id', __NAMESPACE__ . '\InvalidConsumer')
+      ->register('consumer_id0', __NAMESPACE__ . '\ValidConsumer')
+      ->addTag('service_collector');
+    $container
+      ->register('consumer_id1', __NAMESPACE__ . '\InvalidConsumer')
       ->addTag('service_collector');
 
     $handler_pass = new TaggedHandlersPass();