diff --git a/.travis.yml b/.travis.yml
index 9e68280..0a6c248 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -51,6 +51,13 @@ before_script:
   - travis_retry git clone --branch 8.x-1.x --depth 1 https://github.com/Gizra/message_notify.git
   - cd ..
 
+  # Patch Flag for Config Entity flaggings.
+  # @todo Remove once https://www.drupal.org/node/2678756 is committed.
+  - cd modules/flag
+  - curl https://www.drupal.org/files/issues/2678756-20.patch > patch.txt
+  - git apply patch.txt && rm patch.txt
+  - cd -
+
   # Install Composer dependencies on 8.1.x and above.
   - test ${DRUPAL_CORE} == "8.0.x" || composer self-update && composer install
 
diff --git a/config/optional/flag.flag.subscribe_node_type.yml b/config/optional/flag.flag.subscribe_node_type.yml
new file mode 100644
index 0000000..91e09e6
--- /dev/null
+++ b/config/optional/flag.flag.subscribe_node_type.yml
@@ -0,0 +1,26 @@
+langcode: en
+status: true
+dependencies: {  }
+id: subscribe_node_type
+label: 'Content type'
+bundles: {  }
+entity_type: node_type
+enabled: false
+global: false
+weight: 0
+flag_short: Subscribe
+flag_long: ''
+flag_message: 'You are now subscribed to this content type.'
+unflag_short: Unsubscribe
+unflag_long: ''
+unflag_message: 'You are no longer subscribed to this content type.'
+unflag_denied_text: ''
+flag_type: 'entity:node_type'
+link_type: ajax_link
+flagTypeConfig:
+  show_in_links: {  }
+  show_as_field: 1
+  show_on_form: 0
+  show_contextual_link: 0
+linkTypeConfig: {  }
+
diff --git a/message_subscribe_ui/src/Controller/SubscriptionController.php b/message_subscribe_ui/src/Controller/SubscriptionController.php
index f1e939d..2ce7496 100644
--- a/message_subscribe_ui/src/Controller/SubscriptionController.php
+++ b/message_subscribe_ui/src/Controller/SubscriptionController.php
@@ -5,6 +5,7 @@
 use Drupal\Core\Access\AccessResult;
 use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Controller\ControllerBase;
+use Drupal\Core\Entity\ContentEntityTypeInterface;
 use Drupal\Core\Session\AccountInterface;
 use Drupal\Core\Session\AccountProxyInterface;
 use Drupal\flag\FlagInterface;
@@ -146,7 +147,13 @@ public function tab(UserInterface $user, FlagInterface $flag = NULL) {
     if (!$flag) {
       // We are inside /message-subscribe so get the first flag.
       $flags = $this->subscribers->getFlags();
-      $flag = reset($flags);
+
+      // Grab the first non-config entity flag.
+      foreach ($flags as $flag) {
+        if (\Drupal::entityTypeManager()->getDefinition($flag->getFlaggableEntityTypeId()) instanceof ContentEntityTypeInterface) {
+          break;
+        }
+      }
     }
 
     $view = $this->getView($user, $flag);
@@ -165,8 +172,9 @@ public function tab(UserInterface $user, FlagInterface $flag = NULL) {
    * @param \Drupal\flag\FlagInterface $flag
    *   The flag for which to find a matching view.
    *
-   * @return \Drupal\views\ViewExecutable
-   *   The corresponding view executable.
+   * @return \Drupal\views\ViewExecutable|bool
+   *   The corresponding view executable. FALSE if the entity type is not a
+   *   content entity.
    *
    * @throws \Drupal\message_subscribe\Exception\MessageSubscribeException
    *   - If a view corresponding to the `subscribe_ENTITY_TYPE_ID` does not
diff --git a/message_subscribe_ui/src/Plugin/Derivative/MessageSubscribeUiLocalTask.php b/message_subscribe_ui/src/Plugin/Derivative/MessageSubscribeUiLocalTask.php
index 6be1975..2256759 100644
--- a/message_subscribe_ui/src/Plugin/Derivative/MessageSubscribeUiLocalTask.php
+++ b/message_subscribe_ui/src/Plugin/Derivative/MessageSubscribeUiLocalTask.php
@@ -3,6 +3,7 @@
 namespace Drupal\message_subscribe_ui\Plugin\Derivative;
 
 use Drupal\Component\Plugin\Derivative\DeriverBase;
+use Drupal\Core\Entity\ContentEntityTypeInterface;
 use Drupal\Core\Plugin\Discovery\ContainerDeriverInterface;
 use Drupal\message_subscribe\SubscribersInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
@@ -46,6 +47,12 @@ public function getDerivativeDefinitions($base_plugin_definition) {
 
     $first = TRUE;
     foreach ($this->subscribers->getFlags() as $flag) {
+      // @todo Remove this once config entities can have views with
+      // relationships.
+      if (!\Drupal::entityTypeManager()->getDefinition($flag->getFlaggableEntityTypeId()) instanceof ContentEntityTypeInterface) {
+        continue;
+      }
+
       $this->derivatives[$flag->id()] = [
         'title' => $flag->label(),
         // First route gets the same route name as the parent (in order to
diff --git a/tests/src/Kernel/SubscribersTest.php b/tests/src/Kernel/SubscribersTest.php
index 37a6588..87a3149 100644
--- a/tests/src/Kernel/SubscribersTest.php
+++ b/tests/src/Kernel/SubscribersTest.php
@@ -2,9 +2,11 @@
 
 namespace Drupal\Tests\message_subscribe\Kernel;
 
+use Drupal\Component\Utility\Unicode;
 use Drupal\Core\Session\AccountInterface;
 use Drupal\message\Entity\Message;
 use Drupal\message\Entity\MessageTemplate;
+use Drupal\node\Entity\NodeType;
 use Drupal\simpletest\NodeCreationTrait;
 
 /**
@@ -74,6 +76,10 @@ public function setUp() {
     $flag->enable();
     $flag->save();
 
+    $flag = $flags['subscribe_node_type'];
+    $flag->enable();
+    $flag->save();
+
     $this->users[1] = $this->createUser([
       'flag subscribe_node',
       'unflag subscribe_node',
@@ -328,4 +334,24 @@ public function testHooks() {
     ], $uids);
   }
 
+  /**
+   * Tests config entity subscriptions.
+   */
+  public function testConfigEntities() {
+    // Subscribe user 2 to 'article' nodes.
+    $flag = $this->flagService->getFlagById('subscribe_node_type');
+    $node_type = NodeType::create([
+      'type' => Unicode::strtolower($this->randomMachineName()),
+      'name' => $this->randomString(),
+    ]);
+    $node_type->save();
+    $this->flagService->flag($flag, $node_type, $this->users[2]);
+    $message = Message::create([
+      'template' => 'foo',
+      'uid' => $this->users[2],
+    ]);
+    $subscribers = $this->messageSubscribers->getSubscribers($node_type, $message);
+    $this->assertNotEmpty($subscribers[$this->users[2]->id()]);
+  }
+
 }