diff --git a/.drone.yml b/.drone.yml
index ecdb0b6..5243887 100644
--- a/.drone.yml
+++ b/.drone.yml
@@ -15,7 +15,7 @@ steps:
       - composer install --no-progress --no-interaction
 
   - name: run unit tests
-    image: php:7.3
+    image: php:7.4
     commands:
       - vendor/bin/phpunit -c phpunit.xml
 
diff --git a/Dockerfile b/Dockerfile
index 4e28eda..eae1737 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM php:7.3-apache AS base
+FROM php:7.4-apache AS base
 
 WORKDIR /var/www
 
diff --git a/composer.json b/composer.json
index 4e8f2c1..93dcd53 100644
--- a/composer.json
+++ b/composer.json
@@ -12,7 +12,7 @@
         "optimize-autoloader": true
     },
     "require": {
-        "php": "^7.3",
+        "php": "^7.4",
         "ext-pdo": "*",
         "slim/slim": "^4.8",
         "slim/psr7": "^1.3",
diff --git a/composer.lock b/composer.lock
index b68bc5a..183fdc2 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "7ca706ba3c651a07e10e76b10597de60",
+    "content-hash": "7f17e8a8ee73f9262b6c16738ada898d",
     "packages": [
         {
             "name": "fig/http-message-util",
@@ -179,21 +179,21 @@
         },
         {
             "name": "php-di/invoker",
-            "version": "2.3.0",
+            "version": "2.3.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/PHP-DI/Invoker.git",
-                "reference": "992fec6c56f2d1ad1ad5fee28267867c85bfb8f9"
+                "reference": "5214cbe5aad066022cd845dbf313f0e47aed928f"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/PHP-DI/Invoker/zipball/992fec6c56f2d1ad1ad5fee28267867c85bfb8f9",
-                "reference": "992fec6c56f2d1ad1ad5fee28267867c85bfb8f9",
+                "url": "https://api.github.com/repos/PHP-DI/Invoker/zipball/5214cbe5aad066022cd845dbf313f0e47aed928f",
+                "reference": "5214cbe5aad066022cd845dbf313f0e47aed928f",
                 "shasum": ""
             },
             "require": {
                 "php": ">=7.3",
-                "psr/container": "~1.0"
+                "psr/container": "^1.0|^2.0"
             },
             "require-dev": {
                 "athletic/athletic": "~0.1.8",
@@ -222,7 +222,7 @@
             ],
             "support": {
                 "issues": "https://github.com/PHP-DI/Invoker/issues",
-                "source": "https://github.com/PHP-DI/Invoker/tree/2.3.0"
+                "source": "https://github.com/PHP-DI/Invoker/tree/2.3.2"
             },
             "funding": [
                 {
@@ -230,20 +230,20 @@
                     "type": "github"
                 }
             ],
-            "time": "2021-01-15T10:25:40+00:00"
+            "time": "2021-07-30T15:05:32+00:00"
         },
         {
             "name": "php-di/php-di",
-            "version": "6.3.4",
+            "version": "6.3.5",
             "source": {
                 "type": "git",
                 "url": "https://github.com/PHP-DI/PHP-DI.git",
-                "reference": "f53bcba06ab31b18e911b77c039377f4ccd1f7a5"
+                "reference": "b8126d066ce144765300ee0ab040c1ed6c9ef588"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/PHP-DI/PHP-DI/zipball/f53bcba06ab31b18e911b77c039377f4ccd1f7a5",
-                "reference": "f53bcba06ab31b18e911b77c039377f4ccd1f7a5",
+                "url": "https://api.github.com/repos/PHP-DI/PHP-DI/zipball/b8126d066ce144765300ee0ab040c1ed6c9ef588",
+                "reference": "b8126d066ce144765300ee0ab040c1ed6c9ef588",
                 "shasum": ""
             },
             "require": {
@@ -294,7 +294,7 @@
             ],
             "support": {
                 "issues": "https://github.com/PHP-DI/PHP-DI/issues",
-                "source": "https://github.com/PHP-DI/PHP-DI/tree/6.3.4"
+                "source": "https://github.com/PHP-DI/PHP-DI/tree/6.3.5"
             },
             "funding": [
                 {
@@ -306,7 +306,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-06-10T08:04:48+00:00"
+            "time": "2021-09-02T09:49:58+00:00"
         },
         {
             "name": "php-di/phpdoc-reader",
@@ -1054,16 +1054,16 @@
         },
         {
             "name": "symfony/polyfill-mbstring",
-            "version": "v1.23.0",
+            "version": "v1.23.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/polyfill-mbstring.git",
-                "reference": "2df51500adbaebdc4c38dea4c89a2e131c45c8a1"
+                "reference": "9174a3d80210dca8daa7f31fec659150bbeabfc6"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/polyfill-mbstring/zipball/2df51500adbaebdc4c38dea4c89a2e131c45c8a1",
-                "reference": "2df51500adbaebdc4c38dea4c89a2e131c45c8a1",
+                "url": "https://api.github.com/repos/symfony/polyfill-mbstring/zipball/9174a3d80210dca8daa7f31fec659150bbeabfc6",
+                "reference": "9174a3d80210dca8daa7f31fec659150bbeabfc6",
                 "shasum": ""
             },
             "require": {
@@ -1114,7 +1114,7 @@
                 "shim"
             ],
             "support": {
-                "source": "https://github.com/symfony/polyfill-mbstring/tree/v1.23.0"
+                "source": "https://github.com/symfony/polyfill-mbstring/tree/v1.23.1"
             },
             "funding": [
                 {
@@ -1130,20 +1130,20 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-05-27T09:27:20+00:00"
+            "time": "2021-05-27T12:26:48+00:00"
         },
         {
             "name": "symfony/polyfill-php80",
-            "version": "v1.23.0",
+            "version": "v1.23.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/polyfill-php80.git",
-                "reference": "eca0bf41ed421bed1b57c4958bab16aa86b757d0"
+                "reference": "1100343ed1a92e3a38f9ae122fc0eb21602547be"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/polyfill-php80/zipball/eca0bf41ed421bed1b57c4958bab16aa86b757d0",
-                "reference": "eca0bf41ed421bed1b57c4958bab16aa86b757d0",
+                "url": "https://api.github.com/repos/symfony/polyfill-php80/zipball/1100343ed1a92e3a38f9ae122fc0eb21602547be",
+                "reference": "1100343ed1a92e3a38f9ae122fc0eb21602547be",
                 "shasum": ""
             },
             "require": {
@@ -1197,7 +1197,7 @@
                 "shim"
             ],
             "support": {
-                "source": "https://github.com/symfony/polyfill-php80/tree/v1.23.0"
+                "source": "https://github.com/symfony/polyfill-php80/tree/v1.23.1"
             },
             "funding": [
                 {
@@ -1213,7 +1213,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-02-19T12:13:01+00:00"
+            "time": "2021-07-28T13:41:28+00:00"
         },
         {
             "name": "twig/twig",
@@ -1747,33 +1747,33 @@
         },
         {
             "name": "phpspec/prophecy",
-            "version": "1.13.0",
+            "version": "1.14.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpspec/prophecy.git",
-                "reference": "be1996ed8adc35c3fd795488a653f4b518be70ea"
+                "reference": "d86dfc2e2a3cd366cee475e52c6bb3bbc371aa0e"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpspec/prophecy/zipball/be1996ed8adc35c3fd795488a653f4b518be70ea",
-                "reference": "be1996ed8adc35c3fd795488a653f4b518be70ea",
+                "url": "https://api.github.com/repos/phpspec/prophecy/zipball/d86dfc2e2a3cd366cee475e52c6bb3bbc371aa0e",
+                "reference": "d86dfc2e2a3cd366cee475e52c6bb3bbc371aa0e",
                 "shasum": ""
             },
             "require": {
                 "doctrine/instantiator": "^1.2",
-                "php": "^7.2 || ~8.0, <8.1",
+                "php": "^7.2 || ~8.0, <8.2",
                 "phpdocumentor/reflection-docblock": "^5.2",
                 "sebastian/comparator": "^3.0 || ^4.0",
                 "sebastian/recursion-context": "^3.0 || ^4.0"
             },
             "require-dev": {
-                "phpspec/phpspec": "^6.0",
+                "phpspec/phpspec": "^6.0 || ^7.0",
                 "phpunit/phpunit": "^8.0 || ^9.0"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.11.x-dev"
+                    "dev-master": "1.x-dev"
                 }
             },
             "autoload": {
@@ -1808,9 +1808,9 @@
             ],
             "support": {
                 "issues": "https://github.com/phpspec/prophecy/issues",
-                "source": "https://github.com/phpspec/prophecy/tree/1.13.0"
+                "source": "https://github.com/phpspec/prophecy/tree/1.14.0"
             },
-            "time": "2021-03-17T13:42:18+00:00"
+            "time": "2021-09-10T09:02:12+00:00"
         },
         {
             "name": "phpunit/php-code-coverage",
@@ -2132,16 +2132,16 @@
         },
         {
             "name": "phpunit/phpunit",
-            "version": "9.5.7",
+            "version": "9.5.9",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/phpunit.git",
-                "reference": "d0dc8b6999c937616df4fb046792004b33fd31c5"
+                "reference": "ea8c2dfb1065eb35a79b3681eee6e6fb0a6f273b"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/d0dc8b6999c937616df4fb046792004b33fd31c5",
-                "reference": "d0dc8b6999c937616df4fb046792004b33fd31c5",
+                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/ea8c2dfb1065eb35a79b3681eee6e6fb0a6f273b",
+                "reference": "ea8c2dfb1065eb35a79b3681eee6e6fb0a6f273b",
                 "shasum": ""
             },
             "require": {
@@ -2153,7 +2153,7 @@
                 "ext-xml": "*",
                 "ext-xmlwriter": "*",
                 "myclabs/deep-copy": "^1.10.1",
-                "phar-io/manifest": "^2.0.1",
+                "phar-io/manifest": "^2.0.3",
                 "phar-io/version": "^3.0.2",
                 "php": ">=7.3",
                 "phpspec/prophecy": "^1.12.1",
@@ -2219,7 +2219,7 @@
             ],
             "support": {
                 "issues": "https://github.com/sebastianbergmann/phpunit/issues",
-                "source": "https://github.com/sebastianbergmann/phpunit/tree/9.5.7"
+                "source": "https://github.com/sebastianbergmann/phpunit/tree/9.5.9"
             },
             "funding": [
                 {
@@ -2231,7 +2231,7 @@
                     "type": "github"
                 }
             ],
-            "time": "2021-07-19T06:14:47+00:00"
+            "time": "2021-08-31T06:47:40+00:00"
         },
         {
             "name": "sebastian/cli-parser",
@@ -3200,16 +3200,16 @@
         },
         {
             "name": "theseer/tokenizer",
-            "version": "1.2.0",
+            "version": "1.2.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/theseer/tokenizer.git",
-                "reference": "75a63c33a8577608444246075ea0af0d052e452a"
+                "reference": "34a41e998c2183e22995f158c581e7b5e755ab9e"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/theseer/tokenizer/zipball/75a63c33a8577608444246075ea0af0d052e452a",
-                "reference": "75a63c33a8577608444246075ea0af0d052e452a",
+                "url": "https://api.github.com/repos/theseer/tokenizer/zipball/34a41e998c2183e22995f158c581e7b5e755ab9e",
+                "reference": "34a41e998c2183e22995f158c581e7b5e755ab9e",
                 "shasum": ""
             },
             "require": {
@@ -3238,7 +3238,7 @@
             "description": "A small library for converting tokenized PHP source code into XML and potentially other formats",
             "support": {
                 "issues": "https://github.com/theseer/tokenizer/issues",
-                "source": "https://github.com/theseer/tokenizer/tree/master"
+                "source": "https://github.com/theseer/tokenizer/tree/1.2.1"
             },
             "funding": [
                 {
@@ -3246,7 +3246,7 @@
                     "type": "github"
                 }
             ],
-            "time": "2020-07-12T23:59:07+00:00"
+            "time": "2021-07-28T10:34:58+00:00"
         },
         {
             "name": "webmozart/assert",
@@ -3313,9 +3313,9 @@
     "prefer-stable": false,
     "prefer-lowest": false,
     "platform": {
-        "php": "^7.3",
+        "php": "^7.4",
         "ext-pdo": "*"
     },
     "platform-dev": [],
-    "plugin-api-version": "2.0.0"
+    "plugin-api-version": "2.1.0"
 }
diff --git a/src/Common/ActionResult.php b/src/Common/ActionResult.php
index 1db2315..924c489 100644
--- a/src/Common/ActionResult.php
+++ b/src/Common/ActionResult.php
@@ -8,12 +8,9 @@ class ActionResult
     private const STATUS_SUCCESS = 'success';
     private const STATUS_ERROR = 'error';
 
-    /** @var string */
-    private $status;
-    /** @var string */
-    private $message;
-    /** @var null|array */
-    private $inputData;
+    private string $status;
+    private string $message;
+    private ?array $inputData;
 
     private function __construct(string $status, string $message, ?array $inputData = null)
     {
diff --git a/src/Common/UserHelper.php b/src/Common/UserHelper.php
index 38ba0ec..f156459 100644
--- a/src/Common/UserHelper.php
+++ b/src/Common/UserHelper.php
@@ -9,10 +9,8 @@ use MailAccountAdmin\Repositories\AdminUserRepository;
 
 class UserHelper
 {
-    /** @var SessionHelper */
-    private $sessionHelper;
-    /** @var AdminUserRepository */
-    private $adminUserRepository;
+    private SessionHelper $sessionHelper;
+    private AdminUserRepository $adminUserRepository;
 
     public function __construct(SessionHelper $sessionHelper, AdminUserRepository $adminUserRepository)
     {
diff --git a/src/Frontend/Accounts/AccountController.php b/src/Frontend/Accounts/AccountController.php
index b5c403d..0617e56 100644
--- a/src/Frontend/Accounts/AccountController.php
+++ b/src/Frontend/Accounts/AccountController.php
@@ -16,12 +16,9 @@ use Slim\Views\Twig;
 
 class AccountController extends BaseController
 {
-    /** @var AccountHandler */
-    private $accountHandler;
-    /** @var AccountRepository */
-    private $accountRepository;
-    /** @var AliasRepository */
-    private $aliasRepository;
+    private AccountHandler $accountHandler;
+    private AccountRepository $accountRepository;
+    private AliasRepository $aliasRepository;
 
     public function __construct(Twig $view, SessionHelper $sessionHelper, UserHelper $userHelper, AccountHandler $accountHandler, AccountRepository $accountRepository, AliasRepository $aliasRepository)
     {
diff --git a/src/Frontend/Accounts/AccountEditData.php b/src/Frontend/Accounts/AccountEditData.php
index 1422c34..f32553e 100644
--- a/src/Frontend/Accounts/AccountEditData.php
+++ b/src/Frontend/Accounts/AccountEditData.php
@@ -7,20 +7,13 @@ use MailAccountAdmin\Exceptions\InputValidationError;
 
 class AccountEditData
 {
-    /** @var null|string */
-    private $username;
-    /** @var bool */
-    private $usernameCreateAlias;
-    /** @var bool */
-    private $usernameReplaceAlias;
-    /** @var null|string */
-    private $password;
-    /** @var bool */
-    private $active;
-    /** @var null|string */
-    private $homeDir;
-    /** @var null|string */
-    private $memo;
+    private ?string $username;
+    private bool $usernameCreateAlias;
+    private bool $usernameReplaceAlias;
+    private ?string $password;
+    private bool $active;
+    private ?string $homeDir;
+    private ?string $memo;
 
     private function __construct(?string $username, bool $usernameCreateAlias, bool $usernameReplaceAlias, ?string $password, bool $active,
                                  ?string $homeDir, ?string $memo)
diff --git a/src/Frontend/Accounts/AccountHandler.php b/src/Frontend/Accounts/AccountHandler.php
index 62e6c3b..26de4fd 100644
--- a/src/Frontend/Accounts/AccountHandler.php
+++ b/src/Frontend/Accounts/AccountHandler.php
@@ -11,12 +11,9 @@ use MailAccountAdmin\Repositories\AliasRepository;
 
 class AccountHandler
 {
-    /** @var AccountRepository */
-    private $accountRepository;
-    /** @var AliasRepository */
-    private $aliasRepository;
-    /** @var PasswordHelper */
-    private $passwordHelper;
+    private AccountRepository $accountRepository;
+    private AliasRepository $aliasRepository;
+    private PasswordHelper $passwordHelper;
 
     public function __construct(AccountRepository $accountRepository, AliasRepository $aliasRepository, PasswordHelper $passwordHelper)
     {
diff --git a/src/Frontend/BaseController.php b/src/Frontend/BaseController.php
index f460fe4..278fb2e 100644
--- a/src/Frontend/BaseController.php
+++ b/src/Frontend/BaseController.php
@@ -9,12 +9,9 @@ use Slim\Views\Twig;
 
 class BaseController
 {
-    /** @var Twig */
-    protected $view;
-    /** @var SessionHelper */
-    protected $sessionHelper;
-    /** @var UserHelper */
-    protected $userHelper;
+    protected Twig $view;
+    protected SessionHelper $sessionHelper;
+    protected UserHelper $userHelper;
 
     public function __construct(Twig $view, SessionHelper $sessionHelper, UserHelper $userHelper)
     {
diff --git a/src/Frontend/Domains/DomainController.php b/src/Frontend/Domains/DomainController.php
index b1929be..5a9f5db 100644
--- a/src/Frontend/Domains/DomainController.php
+++ b/src/Frontend/Domains/DomainController.php
@@ -13,8 +13,7 @@ use Slim\Views\Twig;
 
 class DomainController extends BaseController
 {
-    /** @var DomainRepository */
-    private $domainRepository;
+    private DomainRepository $domainRepository;
 
     public function __construct(Twig $view, SessionHelper $sessionHelper, UserHelper $userHelper, DomainRepository $domainRepository)
     {
diff --git a/src/Frontend/Login/LoginController.php b/src/Frontend/Login/LoginController.php
index 3e0f875..1d0e530 100644
--- a/src/Frontend/Login/LoginController.php
+++ b/src/Frontend/Login/LoginController.php
@@ -15,10 +15,8 @@ use Slim\Views\Twig;
 
 class LoginController extends BaseController
 {
-    /** @var AdminUserRepository */
-    private $adminUserRepository;
-    /** @var PasswordHelper */
-    private $passwordHelper;
+    private AdminUserRepository $adminUserRepository;
+    private PasswordHelper $passwordHelper;
 
     public function __construct(Twig $view, SessionHelper $sessionHelper, UserHelper $userHelper, AdminUserRepository $adminUserRepository,
                                 PasswordHelper $passwordHelper)
diff --git a/src/Models/Account.php b/src/Models/Account.php
index 472e576..2f67d47 100644
--- a/src/Models/Account.php
+++ b/src/Models/Account.php
@@ -8,32 +8,20 @@ use MailAccountAdmin\Exceptions\InformationUnknownException;
 
 class Account
 {
-    /** @var int */
-    private $id;
-    /** @var string */
-    private $username;
-    /** @var string */
-    private $passwordHash;
-    /** @var bool */
-    private $active;
-    /** @var string */
-    private $homeDir;
-    /** @var string */
-    private $memo;
-    /** @var DateTimeImmutable */
-    private $createdAt;
-    /** @var DateTimeImmutable */
-    private $modifiedAt;
-
-    // Extra data that is not part of the data model
+    private int $id;
+    private string $username;
+    private string $passwordHash;
+    private bool $active;
+    private string $homeDir;
+    private string $memo;
+    private DateTimeImmutable $createdAt;
+    private DateTimeImmutable $modifiedAt;
 
     // Domain (extracted from username)
-    /** @var string */
-    private $domain;
+    private string $domain;
 
     // Number of aliases (not always available)
-    /** @var int|null */
-    private $aliasCount;
+    private ?int $aliasCount;
 
     private function __construct(int $id, string $username, string $passwordHash, bool $active, string $homeDir, string $memo,
                                  DateTimeImmutable $createdAt, DateTimeImmutable $modifiedAt)
diff --git a/src/Models/AdminUser.php b/src/Models/AdminUser.php
index cef9c7b..ae677ac 100644
--- a/src/Models/AdminUser.php
+++ b/src/Models/AdminUser.php
@@ -7,18 +7,12 @@ use DateTimeImmutable;
 
 class AdminUser
 {
-    /** @var int */
-    private $id;
-    /** @var string */
-    private $username;
-    /** @var string */
-    private $passwordHash;
-    /** @var bool */
-    private $active;
-    /** @var DateTimeImmutable */
-    private $createdAt;
-    /** @var DateTimeImmutable */
-    private $modifiedAt;
+    private int $id;
+    private string $username;
+    private string $passwordHash;
+    private bool $active;
+    private DateTimeImmutable $createdAt;
+    private DateTimeImmutable $modifiedAt;
 
     private function __construct(int $id, string $username, string $passwordHash, bool $isActive,
                                  DateTimeImmutable $createdAt, DateTimeImmutable $modifiedAt)
diff --git a/src/Models/Alias.php b/src/Models/Alias.php
index 94e8052..3fe7413 100644
--- a/src/Models/Alias.php
+++ b/src/Models/Alias.php
@@ -7,16 +7,11 @@ use DateTimeImmutable;
 
 class Alias
 {
-    /** @var int */
-    private $id;
-    /** @var int */
-    private $userId;
-    /** @var string */
-    private $mailAddress;
-    /** @var DateTimeImmutable */
-    private $createdAt;
-    /** @var DateTimeImmutable */
-    private $modifiedAt;
+    private int $id;
+    private int $userId;
+    private string $mailAddress;
+    private DateTimeImmutable $createdAt;
+    private DateTimeImmutable $modifiedAt;
 
     private function __construct(int $id, int $userId, string $mailAddress, DateTimeImmutable $createdAt, DateTimeImmutable $modifiedAt)
     {
diff --git a/src/Repositories/BaseRepository.php b/src/Repositories/BaseRepository.php
index 158c55d..24715ff 100644
--- a/src/Repositories/BaseRepository.php
+++ b/src/Repositories/BaseRepository.php
@@ -7,8 +7,7 @@ use PDO;
 
 class BaseRepository
 {
-    /** @var PDO */
-    protected $pdo;
+    protected PDO $pdo;
 
     public function __construct(PDO $pdo)
     {