diff --git a/lib/private/Security/CSRF/CsrfToken.php b/lib/private/Security/CSRF/CsrfToken.php
index d9e27ff80e34bfbb67b76ecf07d1e3bd682a32e4..643e58e1d5334eb5877c43b97f389bcbc9c8324f 100644
--- a/lib/private/Security/CSRF/CsrfToken.php
+++ b/lib/private/Security/CSRF/CsrfToken.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 /**
  * @copyright Copyright (c) 2016, ownCloud, Inc.
  *
@@ -40,7 +41,7 @@ class CsrfToken {
 	/**
 	 * @param string $value Value of the token. Can be encrypted or not encrypted.
 	 */
-	public function __construct($value) {
+	public function __construct(string $value) {
 		$this->value = $value;
 	}
 
@@ -50,9 +51,9 @@ class CsrfToken {
 	 *
 	 * @return string
 	 */
-	public function getEncryptedValue() {
+	public function getEncryptedValue(): string {
 		if($this->encryptedValue === '') {
-			$sharedSecret = random_bytes(strlen($this->value));
+			$sharedSecret = random_bytes(\strlen($this->value));
 			$this->encryptedValue = base64_encode($this->value ^ $sharedSecret) . ':' . base64_encode($sharedSecret);
 		}
 
@@ -65,9 +66,9 @@ class CsrfToken {
 	 *
 	 * @return string
 	 */
-	public function getDecryptedValue() {
+	public function getDecryptedValue(): string {
 		$token = explode(':', $this->value);
-		if (count($token) !== 2) {
+		if (\count($token) !== 2) {
 			return '';
 		}
 		$obfuscatedToken = $token[0];
diff --git a/lib/private/Security/CSRF/CsrfTokenGenerator.php b/lib/private/Security/CSRF/CsrfTokenGenerator.php
index 85207956e1a305675e1dfaa4030ea35afe7c08e4..be628ea176cf6c409835a78af6c5910a0eb1889b 100644
--- a/lib/private/Security/CSRF/CsrfTokenGenerator.php
+++ b/lib/private/Security/CSRF/CsrfTokenGenerator.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 /**
  * @copyright Copyright (c) 2016, ownCloud, Inc.
  *
@@ -47,7 +48,7 @@ class CsrfTokenGenerator {
 	 * @param int $length Length of the token in characters.
 	 * @return string
 	 */
-	public function generateToken($length = 32) {
+	public function generateToken(int $length = 32): string {
 		return $this->random->generate($length);
 	}
 }
diff --git a/lib/private/Security/CSRF/CsrfTokenManager.php b/lib/private/Security/CSRF/CsrfTokenManager.php
index b43ca3d3679f61293fa2b76b265fa1c04d994a5b..deacd1f512cac8bbf67368e02c7d683ece39739d 100644
--- a/lib/private/Security/CSRF/CsrfTokenManager.php
+++ b/lib/private/Security/CSRF/CsrfTokenManager.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 /**
  * @copyright Copyright (c) 2016, ownCloud, Inc.
  *
@@ -52,8 +53,8 @@ class CsrfTokenManager {
 	 *
 	 * @return CsrfToken
 	 */
-	public function getToken() {
-		if(!is_null($this->csrfToken)) {
+	public function getToken(): CsrfToken {
+		if(!\is_null($this->csrfToken)) {
 			return $this->csrfToken;
 		}
 
@@ -73,7 +74,7 @@ class CsrfTokenManager {
 	 *
 	 * @return CsrfToken
 	 */
-	public function refreshToken() {
+	public function refreshToken(): CsrfToken {
 		$value = $this->tokenGenerator->generateToken();
 		$this->sessionStorage->setToken($value);
 		$this->csrfToken = new CsrfToken($value);
@@ -94,7 +95,7 @@ class CsrfTokenManager {
 	 * @param CsrfToken $token
 	 * @return bool
 	 */
-	public function isTokenValid(CsrfToken $token) {
+	public function isTokenValid(CsrfToken $token): bool {
 		if(!$this->sessionStorage->hasToken()) {
 			return false;
 		}
diff --git a/lib/private/Security/CSRF/TokenStorage/SessionStorage.php b/lib/private/Security/CSRF/TokenStorage/SessionStorage.php
index 946330b0c8cb708e8fe58afd4306b8d1d2546793..b35e148c7cebca88f5c908b6c884214a7223147a 100644
--- a/lib/private/Security/CSRF/TokenStorage/SessionStorage.php
+++ b/lib/private/Security/CSRF/TokenStorage/SessionStorage.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 /**
  * @copyright Copyright (c) 2016, ownCloud, Inc.
  *
@@ -54,7 +55,7 @@ class SessionStorage {
 	 * @return string
 	 * @throws \Exception
 	 */
-	public function getToken() {
+	public function getToken(): string {
 		$token = $this->session->get('requesttoken');
 		if(empty($token)) {
 			throw new \Exception('Session does not contain a requesttoken');
@@ -68,7 +69,7 @@ class SessionStorage {
 	 *
 	 * @param string $value
 	 */
-	public function setToken($value) {
+	public function setToken(string $value) {
 		$this->session->set('requesttoken', $value);
 	}
 
@@ -83,7 +84,7 @@ class SessionStorage {
 	 *
 	 * @return bool
 	 */
-	public function hasToken() {
+	public function hasToken(): bool {
 		return $this->session->exists('requesttoken');
 	}
 }
diff --git a/tests/lib/AppFramework/Http/RequestTest.php b/tests/lib/AppFramework/Http/RequestTest.php
index c6b9719b32ae6aa62537d2e76de5a4d6f6dc5a13..a715eaa95993296559769ab17329bcd4abf640ed 100644
--- a/tests/lib/AppFramework/Http/RequestTest.php
+++ b/tests/lib/AppFramework/Http/RequestTest.php
@@ -1846,7 +1846,6 @@ class RequestTest extends \Test\TestCase {
 		return [
 			['InvalidSentToken'],
 			['InvalidSentToken:InvalidSecret'],
-			[null],
 			[''],
 		];
 	}