diff --git a/settings/Controller/ChangePasswordController.php b/settings/Controller/ChangePasswordController.php
index 208178d567..7dbdbac023 100644
--- a/settings/Controller/ChangePasswordController.php
+++ b/settings/Controller/ChangePasswordController.php
@@ -1,5 +1,7 @@
 <?php
-declare(strict_types=1);
+// FIXME: disabled for now to be able to inject IGroupManager and also use
+// getSubAdmin()
+//declare(strict_types=1);
 /**
  *
  *
@@ -27,12 +29,12 @@ declare(strict_types=1);
  */
 namespace OC\Settings\Controller;
 
-use OC\Group\Manager as GroupManager;
 use OC\HintException;
 use OC\User\Session;
 use OCP\App\IAppManager;
 use OCP\AppFramework\Controller;
 use OCP\AppFramework\Http\JSONResponse;
+use OCP\IGroupManager;
 use OCP\IL10N;
 use OCP\IRequest;
 use OCP\IUser;
@@ -50,7 +52,7 @@ class ChangePasswordController extends Controller {
 	/** @var IL10N */
 	private $l;
 
-	/** @var GroupManager */
+	/** @var IGroupManager */
 	private $groupManager;
 
 	/** @var Session */
@@ -64,7 +66,7 @@ class ChangePasswordController extends Controller {
 								string $userId,
 								IUserManager $userManager,
 								IUserSession $userSession,
-								GroupManager $groupManager,
+								IGroupManager $groupManager,
 								IAppManager $appManager,
 								IL10N $l) {
 		parent::__construct($appName, $request);
diff --git a/settings/Controller/UsersController.php b/settings/Controller/UsersController.php
index df89c2ec1a..956403f143 100644
--- a/settings/Controller/UsersController.php
+++ b/settings/Controller/UsersController.php
@@ -1,5 +1,7 @@
 <?php
-declare(strict_types=1);
+// FIXME: disabled for now to be able to inject IGroupManager and also use
+// getSubAdmin()
+//declare(strict_types=1);
 /**
  * @copyright Copyright (c) 2016, ownCloud, Inc.
  *
@@ -40,7 +42,6 @@ namespace OC\Settings\Controller;
 use OC\Accounts\AccountManager;
 use OC\AppFramework\Http;
 use OC\ForbiddenException;
-use OC\Group\Manager as GroupManager;
 use OC\HintException;
 use OC\Settings\Mailer\NewUserMailHelper;
 use OC\Security\IdentityProof\Manager;
@@ -52,6 +53,7 @@ use OCP\Files\Config\IUserMountCache;
 use OCP\Encryption\IEncryptionModule;
 use OCP\Encryption\IManager;
 use OCP\IConfig;
+use OCP\IGroupManager;
 use OCP\IL10N;
 use OCP\ILogger;
 use OCP\IRequest;
@@ -77,7 +79,7 @@ class UsersController extends Controller {
 	private $isAdmin;
 	/** @var IUserManager */
 	private $userManager;
-	/** @var GroupManager */
+	/** @var IGroupManager */
 	private $groupManager;
 	/** @var IConfig */
 	private $config;
@@ -113,7 +115,7 @@ class UsersController extends Controller {
 	public function __construct(string $appName,
 								IRequest $request,
 								IUserManager $userManager,
-								GroupManager $groupManager,
+								IGroupManager $groupManager,
 								IUserSession $userSession,
 								IConfig $config,
 								bool $isAdmin,