diff --git a/lib/private/Federation/CloudId.php b/lib/private/Federation/CloudId.php
index f1d08f0687..4c93650e0f 100644
--- a/lib/private/Federation/CloudId.php
+++ b/lib/private/Federation/CloudId.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 /**
  * @copyright Copyright (c) 2017, Robin Appelman <robin@icewind.nl>
  *
@@ -40,7 +41,7 @@ class CloudId implements ICloudId {
 	 * @param string $user
 	 * @param string $remote
 	 */
-	public function __construct($id, $user, $remote) {
+	public function __construct(string $id, string $user, string $remote) {
 		$this->id = $id;
 		$this->user = $user;
 		$this->remote = $remote;
@@ -51,11 +52,11 @@ class CloudId implements ICloudId {
 	 *
 	 * @return string
 	 */
-	public function getId() {
+	public function getId(): string {
 		return $this->id;
 	}
 
-	public function getDisplayId() {
+	public function getDisplayId(): string {
 		return str_replace('https://', '', str_replace('http://', '', $this->getId()));
 	}
 
@@ -64,7 +65,7 @@ class CloudId implements ICloudId {
 	 *
 	 * @return string
 	 */
-	public function getUser() {
+	public function getUser(): string {
 		return $this->user;
 	}
 
@@ -73,7 +74,7 @@ class CloudId implements ICloudId {
 	 *
 	 * @return string
 	 */
-	public function getRemote() {
+	public function getRemote(): string {
 		return $this->remote;
 	}
 }
diff --git a/lib/private/Federation/CloudIdManager.php b/lib/private/Federation/CloudIdManager.php
index 3b7aaae539..0beb6cf6d2 100644
--- a/lib/private/Federation/CloudIdManager.php
+++ b/lib/private/Federation/CloudIdManager.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 /**
  * @copyright Copyright (c) 2017, Robin Appelman <robin@icewind.nl>
  *
@@ -33,7 +34,7 @@ class CloudIdManager implements ICloudIdManager {
 	 * @return ICloudId
 	 * @throws \InvalidArgumentException
 	 */
-	public function resolveCloudId($cloudId) {
+	public function resolveCloudId(string $cloudId): ICloudId {
 		// TODO magic here to get the url and user instead of just splitting on @
 
 		if (!$this->isValidCloudId($cloudId)) {
@@ -46,7 +47,7 @@ class CloudIdManager implements ICloudIdManager {
 		$posColon = strpos($id, ':');
 
 		if ($posSlash === false && $posColon === false) {
-			$invalidPos = strlen($id);
+			$invalidPos = \strlen($id);
 		} else if ($posSlash === false) {
 			$invalidPos = $posColon;
 		} else if ($posColon === false) {
@@ -77,7 +78,7 @@ class CloudIdManager implements ICloudIdManager {
 	 * @param string $remote
 	 * @return CloudId
 	 */
-	public function getCloudId($user, $remote) {
+	public function getCloudId(string $user, string $remote): ICloudId {
 		// TODO check what the correct url is for remote (asking the remote)
 		return new CloudId($user. '@' . $remote, $user, $remote);
 	}
@@ -94,7 +95,7 @@ class CloudIdManager implements ICloudIdManager {
 	 * @param string $remote
 	 * @return string
 	 */
-	protected function fixRemoteURL($remote) {
+	protected function fixRemoteURL(string $remote): string {
 		$remote = str_replace('\\', '/', $remote);
 		if ($fileNamePosition = strpos($remote, '/index.php')) {
 			$remote = substr($remote, 0, $fileNamePosition);
@@ -108,7 +109,7 @@ class CloudIdManager implements ICloudIdManager {
 	 * @param string $cloudId
 	 * @return bool
 	 */
-	public function isValidCloudId($cloudId) {
+	public function isValidCloudId(string $cloudId): bool {
 		return strpos($cloudId, '@') !== false;
 	}
 }
diff --git a/lib/public/Federation/ICloudId.php b/lib/public/Federation/ICloudId.php
index b03acb4f5f..6cc17984f9 100644
--- a/lib/public/Federation/ICloudId.php
+++ b/lib/public/Federation/ICloudId.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 /**
  * @copyright Copyright (c) 2017, Robin Appelman <robin@icewind.nl>
  *
@@ -35,7 +36,7 @@ interface ICloudId {
 	 * @return string
 	 * @since 12.0.0
 	 */
-	public function getId();
+	public function getId(): string;
 
 	/**
 	 * Get a clean representation of the cloud id for display
@@ -43,7 +44,7 @@ interface ICloudId {
 	 * @return string
 	 * @since 12.0.0
 	 */
-	public function getDisplayId();
+	public function getDisplayId(): string;
 
 	/**
 	 * The username on the remote server
@@ -51,7 +52,7 @@ interface ICloudId {
 	 * @return string
 	 * @since 12.0.0
 	 */
-	public function getUser();
+	public function getUser(): string;
 
 	/**
 	 * The base address of the remote server
@@ -59,5 +60,5 @@ interface ICloudId {
 	 * @return string
 	 * @since 12.0.0
 	 */
-	public function getRemote();
+	public function getRemote(): string;
 }
diff --git a/lib/public/Federation/ICloudIdManager.php b/lib/public/Federation/ICloudIdManager.php
index b5b3436e6f..c139cfda6c 100644
--- a/lib/public/Federation/ICloudIdManager.php
+++ b/lib/public/Federation/ICloudIdManager.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 /**
  * @copyright Copyright (c) 2017, Robin Appelman <robin@icewind.nl>
  *
@@ -37,7 +38,7 @@ interface ICloudIdManager {
 	 *
 	 * @since 12.0.0
 	 */
-	public function resolveCloudId($cloudId);
+	public function resolveCloudId(string $cloudId): ICloudId;
 
 	/**
 	 * Get the cloud id for a remote user
@@ -48,7 +49,7 @@ interface ICloudIdManager {
 	 *
 	 * @since 12.0.0
 	 */
-	public function getCloudId($user, $remote);
+	public function getCloudId(string $user, string $remote): ICloudId;
 
 	/**
 	 * Check if the input is a correctly formatted cloud id
@@ -58,5 +59,5 @@ interface ICloudIdManager {
 	 *
 	 * @since 12.0.0
 	 */
-	public function isValidCloudId($cloudId);
+	public function isValidCloudId(string $cloudId): bool;
 }