diff --git a/.envrc b/.envrc
index 1d953f4..1b5ce28 100644
--- a/.envrc
+++ b/.envrc
@@ -1 +1,2 @@
 use nix
+watch_file flake.nix flake.lock
diff --git a/.github/workflows/main.yaml b/.github/workflows/main.yaml
index da0908a..6095ec7 100644
--- a/.github/workflows/main.yaml
+++ b/.github/workflows/main.yaml
@@ -10,16 +10,16 @@ env:
 
 jobs:
   tests:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
     strategy:
       matrix:
         php:
+          - '8.4'
+          - '8.3'
           - '8.2'
           - '8.1'
           - '8.0'
           - '7.4'
-          - '7.3'
-          - '7.2'
         include:
           - php: '7.4'
             cs_fixer: true
@@ -27,13 +27,13 @@ jobs:
             phpstan: true
     name: 'Check with PHP ${{ matrix.php }}'
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Install Nix
-        uses: cachix/install-nix-action@v20
+        uses: cachix/install-nix-action@v31
 
       - name: Set up Nix cache
-        uses: cachix/cachix-action@v12
+        uses: cachix/cachix-action@v16
         with:
           # Use cache from https://github.com/fossar/nix-phps
           name: fossar
@@ -46,7 +46,7 @@ jobs:
         run: |
           echo "dir=$(composer config cache-files-dir)" >> "$GITHUB_OUTPUT"
 
-      - uses: actions/cache@v3
+      - uses: actions/cache@v4
         with:
           path: ${{ steps.composer-cache.outputs.dir }}
           key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.lock') }}
diff --git a/.gitignore b/.gitignore
index 987e2a2..5509604 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,6 @@
 composer.lock
-vendor
+vendor/
+.direnv/
+.php-cs-fixer.cache
+.phpunit.result.cache
+phpstan.neon
diff --git a/.php-cs-fixer.php b/.php-cs-fixer.php
index bd56d62..f0f592f 100644
--- a/.php-cs-fixer.php
+++ b/.php-cs-fixer.php
@@ -5,9 +5,10 @@
 
 $rules = [
     '@Symfony' => true,
-    '@PHP71Migration' => true,
-    '@PHP71Migration:risky' => true,
-    'phpdoc_to_param_type' => true,
+    '@PHP74Migration' => true,
+    '@PHP74Migration:risky' => true,
+    'phpdoc_to_property_type' => true,
+    // 'phpdoc_to_param_type' => true, // requires PHP 8.0
     'phpdoc_to_return_type' => true,
     // overwrite some Symfony rules
     'concat_space' => ['spacing' => 'one'],
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0ed47bf..92654a5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 ## [3.0.0] – unreleased
 
 - Mb: Make encoding detection stricter.
+- Raise minimum PHP version to 7.4.0.
 
 
 ## [2.0.0] – 2023-03-07
diff --git a/composer.json b/composer.json
index 642dfad..1575f4f 100644
--- a/composer.json
+++ b/composer.json
@@ -17,10 +17,12 @@
         "ddeboer/transcoder": "self.version"
     },
     "require": {
-        "php": ">=7.2.5"
+        "php": ">=7.4.0"
     },
     "require-dev": {
-        "symfony/phpunit-bridge": "^6.2"
+        "symfony/phpunit-bridge": "^6.2 || ^7.0",
+        "phpstan/phpstan": "^2.1",
+        "friendsofphp/php-cs-fixer": "^3.4"
     },
     "suggest": {
         "ext-mbstring": "For using the MbTranscoder",
@@ -34,7 +36,7 @@
     },
     "config": {
         "platform": {
-            "php": "7.2.5"
+            "php": "7.4.0"
         }
     },
     "scripts": {
diff --git a/flake.lock b/flake.lock
index 6b23d4c..ed532a6 100644
--- a/flake.lock
+++ b/flake.lock
@@ -3,11 +3,11 @@
     "flake-compat": {
       "flake": false,
       "locked": {
-        "lastModified": 1673956053,
-        "narHash": "sha256-4gtG9iQuiKITOjNQQeQIpoIB6b16fm+504Ch3sNKLd8=",
+        "lastModified": 1733328505,
+        "narHash": "sha256-NeCCThCEP3eCl2l/+27kNNK7QrwZB1IJCrXfrbv5oqU=",
         "owner": "edolstra",
         "repo": "flake-compat",
-        "rev": "35bb57c0c8d8b62bbfd284272c928ceb64ddbde9",
+        "rev": "ff81ac966bb2cae68946d5ed5fc4994f96d0ffec",
         "type": "github"
       },
       "original": {
@@ -18,11 +18,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1677852945,
-        "narHash": "sha256-liiVJjkBTuBTAkRW3hrI8MbPD2ImYzwUpa7kvteiKhM=",
+        "lastModified": 1741310760,
+        "narHash": "sha256-aizILFrPgq/W53Jw8i0a1h1GZAAKtlYOrG/A5r46gVM=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "f5ffd5787786dde3a8bf648c7a1b5f78c4e01abb",
+        "rev": "de0fe301211c267807afd11b12613f5511ff7433",
         "type": "github"
       },
       "original": {
@@ -39,11 +39,11 @@
         "utils": "utils"
       },
       "locked": {
-        "lastModified": 1678028979,
-        "narHash": "sha256-qFSN1sKlavyqUl9Vz60+iniYbTLfXtdAwFmTDdlLN5o=",
+        "lastModified": 1741586946,
+        "narHash": "sha256-EI5TFGNt2ObkK8MdBASS9LVkWT0qTqOljFFP2+RjZI0=",
         "owner": "fossar",
         "repo": "nix-phps",
-        "rev": "181dee32f3d47312674462cff30fcca661c6c643",
+        "rev": "e48727edd2dbbbd7b9181bd284569554f6e4e5a6",
         "type": "github"
       },
       "original": {
@@ -57,13 +57,31 @@
         "phps": "phps"
       }
     },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    },
     "utils": {
+      "inputs": {
+        "systems": "systems"
+      },
       "locked": {
-        "lastModified": 1676283394,
-        "narHash": "sha256-XX2f9c3iySLCw54rJ/CZs+ZK6IQy7GXNY4nSOyu2QG4=",
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
         "owner": "numtide",
         "repo": "flake-utils",
-        "rev": "3db36a8b464d0c4532ba1c7dda728f4576d6d073",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
         "type": "github"
       },
       "original": {
diff --git a/flake.nix b/flake.nix
index 70de764..44217c7 100644
--- a/flake.nix
+++ b/flake.nix
@@ -48,10 +48,12 @@
             # Composer and PHP.
             php
             phpBase.packages.composer
-
-            phpBase.packages.php-cs-fixer
-            phpBase.packages.phpstan
+            pkgs.phpactor
           ];
+
+          env = pkgs.lib.optionalAttrs pkgs.stdenv.hostPlatform.isLinux {
+            LOCALE_ARCHIVE = "${pkgs.glibcLocales}/lib/locale/locale-archive";
+          };
         };
       };
 }
diff --git a/phpstan.neon b/phpstan.dist.neon
similarity index 100%
rename from phpstan.neon
rename to phpstan.dist.neon
diff --git a/src/IconvTranscoder.php b/src/IconvTranscoder.php
index ff09cc3..09da620 100644
--- a/src/IconvTranscoder.php
+++ b/src/IconvTranscoder.php
@@ -10,10 +10,7 @@
 
 class IconvTranscoder implements TranscoderInterface
 {
-    /**
-     * @var string
-     */
-    private $defaultEncoding;
+    private string $defaultEncoding;
 
     /**
      * Create an Iconv-based transcoder.
@@ -29,9 +26,6 @@ public function __construct(string $defaultEncoding = 'UTF-8')
         $this->defaultEncoding = $defaultEncoding;
     }
 
-    /**
-     * {@inheritdoc}
-     */
     public function transcode(string $string, ?string $from = null, ?string $to = null): string
     {
         set_error_handler(
diff --git a/src/MbTranscoder.php b/src/MbTranscoder.php
index 232f44e..91ca423 100644
--- a/src/MbTranscoder.php
+++ b/src/MbTranscoder.php
@@ -13,12 +13,9 @@ class MbTranscoder implements TranscoderInterface
     /**
      * @var array<string, int>
      */
-    private static $encodings;
+    private static array $encodings;
 
-    /**
-     * @var string
-     */
-    private $defaultEncoding;
+    private string $defaultEncoding;
 
     /**
      * Create a Mb-based transcoder.
@@ -31,7 +28,7 @@ public function __construct(string $defaultEncoding = 'UTF-8')
             throw new ExtensionMissingException('mb');
         }
 
-        if (null === self::$encodings) {
+        if (!isset(self::$encodings)) {
             self::$encodings = array_change_key_case(
                 array_flip(mb_list_encodings()),
                 CASE_LOWER
@@ -43,8 +40,6 @@ public function __construct(string $defaultEncoding = 'UTF-8')
     }
 
     /**
-     * {@inheritdoc}
-     *
      * @param array<string>|string|null $from
      */
     public function transcode(string $string, $from = null, ?string $to = null): string
@@ -77,9 +72,6 @@ public function transcode(string $string, $from = null, ?string $to = null): str
             $from
         );
 
-        // For PHPStan: We check the encoding is valid.
-        assert($result !== false);
-
         return $result;
     }
 
diff --git a/src/Transcoder.php b/src/Transcoder.php
index 7f71782..f43b0d8 100644
--- a/src/Transcoder.php
+++ b/src/Transcoder.php
@@ -12,12 +12,12 @@ class Transcoder implements TranscoderInterface
     /**
      * @var array<string, TranscoderInterface>
      */
-    private static $chain;
+    private static array $chain;
 
     /**
      * @var TranscoderInterface[]
      */
-    private $transcoders = [];
+    private array $transcoders = [];
 
     /**
      * @param TranscoderInterface[] $transcoders
@@ -27,9 +27,6 @@ public function __construct(array $transcoders)
         $this->transcoders = $transcoders;
     }
 
-    /**
-     * {@inheritdoc}
-     */
     public function transcode(string $string, ?string $from = null, ?string $to = null): string
     {
         foreach ($this->transcoders as $transcoder) {
diff --git a/tests/IconvTranscoderTest.php b/tests/IconvTranscoderTest.php
index 64f8aa8..95eda5f 100644
--- a/tests/IconvTranscoderTest.php
+++ b/tests/IconvTranscoderTest.php
@@ -8,10 +8,7 @@
 
 class IconvTranscoderTest extends \PHPUnit\Framework\TestCase
 {
-    /**
-     * @var IconvTranscoder
-     */
-    private $transcoder;
+    private IconvTranscoder $transcoder;
 
     /**
      * @before
diff --git a/tests/MbTranscoderTest.php b/tests/MbTranscoderTest.php
index 97e9077..6735d71 100644
--- a/tests/MbTranscoderTest.php
+++ b/tests/MbTranscoderTest.php
@@ -8,10 +8,7 @@
 
 class MbTranscoderTest extends \PHPUnit\Framework\TestCase
 {
-    /**
-     * @var MbTranscoder
-     */
-    private $transcoder;
+    private MbTranscoder $transcoder;
 
     /**
      * @before
diff --git a/tests/TranscoderTest.php b/tests/TranscoderTest.php
index d1d78a6..77f7b89 100644
--- a/tests/TranscoderTest.php
+++ b/tests/TranscoderTest.php
@@ -9,10 +9,7 @@
 
 class TranscoderTest extends \PHPUnit\Framework\TestCase
 {
-    /**
-     * @var TranscoderInterface
-     */
-    private $transcoder;
+    private TranscoderInterface $transcoder;
 
     /**
      * @before