diff --git a/apps/workflowengine/appinfo/routes.php b/apps/workflowengine/appinfo/routes.php
index 69478b1715..b8c9ae1c23 100644
--- a/apps/workflowengine/appinfo/routes.php
+++ b/apps/workflowengine/appinfo/routes.php
@@ -21,7 +21,6 @@
 
 return [
 	'routes' => [
-		['name' => 'flowOperations#getChecks', 'url' => '/checks', 'verb' => 'GET'], // TODO rm and do via js?
 		['name' => 'flowOperations#getOperations', 'url' => '/operations', 'verb' => 'GET'],
 		['name' => 'flowOperations#addOperation', 'url' => '/operations', 'verb' => 'POST'],
 		['name' => 'flowOperations#updateOperation', 'url' => '/operations/{id}', 'verb' => 'PUT'],
diff --git a/apps/workflowengine/lib/AppInfo/Application.php b/apps/workflowengine/lib/AppInfo/Application.php
index c196ecd955..8433950304 100644
--- a/apps/workflowengine/lib/AppInfo/Application.php
+++ b/apps/workflowengine/lib/AppInfo/Application.php
@@ -37,18 +37,6 @@ class Application extends \OCP\AppFramework\App {
 	 */
 	public function registerHooksAndListeners() {
 		$dispatcher = $this->getContainer()->getServer()->getEventDispatcher();
-		$dispatcher->addListener(
-			'OCP\WorkflowEngine\RegisterCheckEvent',
-			function(RegisterCheckEvent $event) {
-				$event->addCheck(
-					'OCA\WorkflowEngine\Check\UserGroupMembership',
-					'User group membership',
-					['is', '!is']
-				);
-			},
-			-100
-		);
-
 		$dispatcher->addListener(
 			'OCP\WorkflowEngine::loadAdditionalSettingScripts',
 			function() {
diff --git a/apps/workflowengine/lib/Controller/FlowOperations.php b/apps/workflowengine/lib/Controller/FlowOperations.php
index e0836c727a..94b8b9ddc7 100644
--- a/apps/workflowengine/lib/Controller/FlowOperations.php
+++ b/apps/workflowengine/lib/Controller/FlowOperations.php
@@ -26,38 +26,19 @@ use OCP\AppFramework\Controller;
 use OCP\AppFramework\Http;
 use OCP\AppFramework\Http\JSONResponse;
 use OCP\IRequest;
-use OCP\WorkflowEngine\RegisterCheckEvent;
-use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 
 class FlowOperations extends Controller {
 
 	/** @var Manager */
 	protected $manager;
 
-	/** @var EventDispatcherInterface */
-	protected $dispatcher;
-
 	/**
 	 * @param IRequest $request
 	 * @param Manager $manager
-	 * @param EventDispatcherInterface $dispatcher
 	 */
-	public function __construct(IRequest $request, Manager $manager, EventDispatcherInterface $dispatcher) {
+	public function __construct(IRequest $request, Manager $manager) {
 		parent::__construct('workflowengine', $request);
 		$this->manager = $manager;
-		$this->dispatcher = $dispatcher;
-	}
-
-	/**
-	 * @NoCSRFRequired
-	 *
-	 * @return JSONResponse
-	 */
-	public function getChecks() {
-		$event = new RegisterCheckEvent();
-		$this->dispatcher->dispatch('OCP\WorkflowEngine\RegisterCheckEvent', $event);
-
-		return new JSONResponse($event->getChecks());
 	}
 
 	/**
diff --git a/apps/workflowengine/lib/Manager.php b/apps/workflowengine/lib/Manager.php
index 98c34e894c..f2a04dfb0f 100644
--- a/apps/workflowengine/lib/Manager.php
+++ b/apps/workflowengine/lib/Manager.php
@@ -110,8 +110,8 @@ class Manager implements IManager {
 			$checkInstance->setFileInfo($this->storage, $this->path);
 			return $checkInstance->executeCheck($check['operator'], $check['value']);
 		} else {
-			// Check is invalid, assume it matches.
-			return true;
+			// Check is invalid
+			throw new \RuntimeException('Check ' . htmlspecialchars($check['class']) . ' is invalid or does not exist');
 		}
 	}
 
@@ -258,10 +258,12 @@ class Manager implements IManager {
 		}
 		$result->closeCursor();
 
-		// TODO What if a check is missing? Should we throw?
-		// As long as we only allow AND-concatenation of checks, a missing check
-		// is like a matching check, so it evaluates to true and therefor blocks
-		// access. So better save than sorry.
+		$checkIds = array_diff($checkIds, array_keys($checks));
+
+		if (!empty($checkIds)) {
+			$missingCheck = array_pop($checkIds);
+			throw new \RuntimeException('Check #' . htmlspecialchars($missingCheck) . ' is invalid or does not exist');
+		}
 
 		return $checks;
 	}
diff --git a/lib/public/WorkflowEngine/RegisterCheckEvent.php b/lib/public/WorkflowEngine/RegisterCheckEvent.php
deleted file mode 100644
index e08aae5fbc..0000000000
--- a/lib/public/WorkflowEngine/RegisterCheckEvent.php
+++ /dev/null
@@ -1,79 +0,0 @@
-<?php
-/**
- * @copyright Copyright (c) 2016 Morris Jobke <hey@morrisjobke.de>
- *
- * @license GNU AGPL version 3 or any later version
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License as
- * published by the Free Software Foundation, either version 3 of the
- * License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- */
-
-namespace OCP\WorkflowEngine;
-
-
-use Symfony\Component\EventDispatcher\Event;
-
-/**
- * Class RegisterCheckEvent
- *
- * @package OCP\WorkflowEngine
- * @since 9.1
- */
-class RegisterCheckEvent extends Event {
-
-	/** @var array[] */
-	protected $checks = [];
-
-	/**
-	 * @param string $class
-	 * @param string $name
-	 * @param string[] $operators
-	 * @throws \OutOfBoundsException when the check class is already registered
-	 * @throws \OutOfBoundsException when the provided information is invalid
-	 * @since 9.1
-	 */
-	public function addCheck($class, $name, array $operators) {
-		if (!is_string($class)) {
-			throw new \OutOfBoundsException('Given class name is not a string');
-		}
-
-		if (isset($this->checks[$class])) {
-			throw new \OutOfBoundsException('Duplicate check class "' . $class . '"');
-		}
-
-		if (!is_string($name)) {
-			throw new \OutOfBoundsException('Given check name is not a string');
-		}
-
-		foreach ($operators as $operator) {
-			if (!is_string($operator)) {
-				throw new \OutOfBoundsException('At least one of the operators is not a string');
-			}
-		}
-
-		$this->checks[$class] = [
-			'class' => $class,
-			'name' => $name,
-			'operators' => $operators,
-		];
-	}
-
-	/**
-	 * @return array[]
-	 * @since 9.1
-	 */
-	public function getChecks() {
-		return array_values($this->checks);
-	}
-}