diff --git a/.gitattributes b/.gitattributes
index c8f9f28..8d981ed 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -1,12 +1,12 @@
-/benchmark       export-ignore
-/static-analysis export-ignore
-/tests           export-ignore
-.gitattributes   export-ignore
-.gitignore       export-ignore
-.php_cs          export-ignore
-.travis.yml      export-ignore
-composer.lock    export-ignore
-phpbench.json    export-ignore
-phpunit.xml.dist export-ignore
-psalm.xml        export-ignore
-rector.php       export-ignore
+/benchmark        export-ignore
+/static-analysis  export-ignore
+/tests            export-ignore
+.gitattributes    export-ignore
+.gitignore        export-ignore
+.php-cs-fixer.php export-ignore
+.travis.yml       export-ignore
+composer.lock     export-ignore
+phpbench.json     export-ignore
+phpunit.xml.dist  export-ignore
+psalm.xml         export-ignore
+rector.php        export-ignore
diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index 8160475..8dc3778 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -40,6 +40,10 @@ jobs:
         with:
           dependency-versions: "${{ matrix.dependencies }}"
 
+      - name: "Check code style"
+        if: ${{ matrix.dependencies == 'highest' && matrix.php == '8.1' }}
+        run: composer code-style:check
+
       - name: "Run psalm"
         run: vendor/bin/psalm
 
diff --git a/.gitignore b/.gitignore
index 030990c..10d1207 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@
 .idea
 .phpunit.result.cache
+.php-cs-fixer.cache
 /phpunit.xml
 /vendor/
diff --git a/.php-cs-fixer.php b/.php-cs-fixer.php
new file mode 100644
index 0000000..b07cca6
--- /dev/null
+++ b/.php-cs-fixer.php
@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+$finder = \PhpCsFixer\Finder::create()
+    ->in(__DIR__)
+;
+
+return (new \PhpCsFixer\Config())->setRiskyAllowed(true)
+    ->setRules([
+        '@PHP81Migration' => true,
+        '@Symfony' => true,
+        'yoda_style' => false,
+
+    ])
+    ->setFinder($finder)
+;
diff --git a/.php_cs b/.php_cs
deleted file mode 100644
index 62bdf01..0000000
--- a/.php_cs
+++ /dev/null
@@ -1,15 +0,0 @@
-<?php
-
-return PhpCsFixer\Config::create()
-    ->setRules([
-        '@Symfony' => true,
-        '@PSR1' => true,
-        'blank_line_before_return' => true,
-    ])
-    ->setFinder(
-        PhpCsFixer\Finder::create()
-            ->in(__DIR__.DIRECTORY_SEPARATOR.'src')
-            ->in(__DIR__.DIRECTORY_SEPARATOR.'tests')
-    )
-    ->setRiskyAllowed(true)
-    ->setUsingCache(true);
diff --git a/benchmark/BaseShorteningBench.php b/benchmark/BaseShorteningBench.php
index 22974f2..c4fa14e 100644
--- a/benchmark/BaseShorteningBench.php
+++ b/benchmark/BaseShorteningBench.php
@@ -5,7 +5,6 @@
 namespace Benchmark\Keiko\Uuid\Shortener;
 
 use Keiko\Uuid\Shortener\Shortener;
-use function array_map;
 
 abstract class BaseShorteningBench
 {
@@ -145,7 +144,7 @@ public function benchShorteningOfHugeUuid(): void
 
     public function benchShorteningOfPromiscuousUuids(): void
     {
-        array_map($this->shortener->reduce(...), self::UUIDS_TO_BE_SHORTENED);
+        \array_map($this->shortener->reduce(...), self::UUIDS_TO_BE_SHORTENED);
     }
 
     public function benchExpandingOfTinyUuid(): void
@@ -160,6 +159,6 @@ public function benchExpandingOfHugeUuid(): void
 
     public function benchExpandingOfPromiscuousUuids(): void
     {
-        array_map($this->shortener->expand(...), $this->shortenedPromoscuousUuids);
+        \array_map($this->shortener->expand(...), $this->shortenedPromoscuousUuids);
     }
 }
diff --git a/benchmark/GMPShortenerBench.php b/benchmark/GMPShortenerBench.php
index 1a8292e..0753cee 100644
--- a/benchmark/GMPShortenerBench.php
+++ b/benchmark/GMPShortenerBench.php
@@ -10,7 +10,7 @@
 
 final class GMPShortenerBench extends BaseShorteningBench
 {
-    protected function newShortener() : Shortener
+    protected function newShortener(): Shortener
     {
         return new GMPShortener(Dictionary::createUnmistakable());
     }
diff --git a/benchmark/ShortenerBench.php b/benchmark/ShortenerBench.php
index 31dfbbf..e70b369 100644
--- a/benchmark/ShortenerBench.php
+++ b/benchmark/ShortenerBench.php
@@ -10,7 +10,7 @@
 
 final class ShortenerBench extends BaseShorteningBench
 {
-    protected function newShortener() : Shortener
+    protected function newShortener(): Shortener
     {
         return new Shortener(Dictionary::createUnmistakable(), new Converter());
     }
diff --git a/composer.json b/composer.json
index 8f9455f..dc5031d 100644
--- a/composer.json
+++ b/composer.json
@@ -28,7 +28,8 @@
     "phpunit/phpunit": "^8.5.26",
     "vimeo/psalm": "^4.3.1",
     "phpbench/phpbench": "^1.1.1",
-    "rector/rector": "^0.18.12"
+    "rector/rector": "^0.18.12",
+    "php-cs-fixer/shim": "^3.41"
   },
   "suggest": {
     "ramsey/uuid": "A PHP 5.4+ library for generating RFC 4122 version 1, 3, 4, and 5 universally unique identifiers (UUID)",
@@ -49,6 +50,8 @@
     }
   },
   "scripts": {
+    "code-style:check": "php-cs-fixer fix --dry-run --diff --ansi",
+    "code-style:fix": "php-cs-fixer fix --diff --ansi",
     "rector:check": "rector --dry-run --ansi",
     "rector:fix": "rector --ansi"
   }
diff --git a/composer.lock b/composer.lock
index 4159efd..19d6beb 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": "ef4e44e777a7c7a30a3c907cde2e411a",
+    "content-hash": "9381d119d8758e179bf31e6bb8d8e6ec",
     "packages": [
         {
             "name": "brick/math",
@@ -1264,6 +1264,58 @@
             },
             "time": "2022-02-21T01:04:05+00:00"
         },
+        {
+            "name": "php-cs-fixer/shim",
+            "version": "v3.41.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/PHP-CS-Fixer/shim.git",
+                "reference": "01cea2dca727100537bd63e28e06e49a475b54e9"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/PHP-CS-Fixer/shim/zipball/01cea2dca727100537bd63e28e06e49a475b54e9",
+                "reference": "01cea2dca727100537bd63e28e06e49a475b54e9",
+                "shasum": ""
+            },
+            "require": {
+                "ext-json": "*",
+                "ext-tokenizer": "*",
+                "php": "^7.4 || ^8.0"
+            },
+            "replace": {
+                "friendsofphp/php-cs-fixer": "self.version"
+            },
+            "suggest": {
+                "ext-dom": "For handling output formats in XML",
+                "ext-mbstring": "For handling non-UTF8 characters."
+            },
+            "bin": [
+                "php-cs-fixer",
+                "php-cs-fixer.phar"
+            ],
+            "type": "application",
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Fabien Potencier",
+                    "email": "fabien@symfony.com"
+                },
+                {
+                    "name": "Dariusz Rumiński",
+                    "email": "dariusz.ruminski@gmail.com"
+                }
+            ],
+            "description": "A tool to automatically fix PHP code style",
+            "support": {
+                "issues": "https://github.com/PHP-CS-Fixer/shim/issues",
+                "source": "https://github.com/PHP-CS-Fixer/shim/tree/v3.41.1"
+            },
+            "time": "2023-12-10T19:59:57+00:00"
+        },
         {
             "name": "phpbench/container",
             "version": "2.2.2",
diff --git a/src/Dictionary.php b/src/Dictionary.php
index 6e9745a..2cf006d 100644
--- a/src/Dictionary.php
+++ b/src/Dictionary.php
@@ -5,10 +5,6 @@
 namespace Keiko\Uuid\Shortener;
 
 use Keiko\Uuid\Shortener\Exception\DictionaryException;
-use function array_flip;
-use function count_chars;
-use function str_split;
-use function strlen;
 
 /** @psalm-immutable */
 final class Dictionary
@@ -34,25 +30,23 @@ final class Dictionary
      */
     public function __construct(string $charsSet)
     {
-        $length = strlen($charsSet);
+        $length = \strlen($charsSet);
 
         if ($length <= 16) {
             throw DictionaryException::charsSetTooShort();
         }
 
-        $uniqueChars = count_chars($charsSet, 3);
-        if (strlen($uniqueChars) !== $length) {
+        $uniqueChars = \count_chars($charsSet, 3);
+        if (\strlen($uniqueChars) !== $length) {
             throw DictionaryException::nonUniqueChars();
         }
 
         $this->charsSet = $charsSet;
         $this->length = $length;
-        $this->charIndexes = array_flip(str_split($charsSet));
+        $this->charIndexes = \array_flip(\str_split($charsSet));
     }
 
     /**
-     * @return Dictionary
-     *
      * @psalm-pure
      */
     public static function createUnmistakable(): Dictionary
@@ -61,8 +55,6 @@ public static function createUnmistakable(): Dictionary
     }
 
     /**
-     * @return Dictionary
-     *
      * @psalm-pure
      */
     public static function createAlphanumeric(): Dictionary
@@ -70,9 +62,6 @@ public static function createAlphanumeric(): Dictionary
         return new self(self::DICTIONARY_ALPHANUMERIC);
     }
 
-    /**
-     * @return int
-     */
     public function getLength(): int
     {
         return $this->length;
@@ -80,8 +69,6 @@ public function getLength(): int
 
     /**
      * @throws DictionaryException
-     *
-     * @return string
      */
     public function getCharAt(int $index): string
     {
@@ -94,8 +81,6 @@ public function getCharAt(int $index): string
 
     /**
      * @throws DictionaryException
-     *
-     * @return int
      */
     public function getCharIndex(string $char): int
     {
diff --git a/src/GMPShortener.php b/src/GMPShortener.php
index d11bd0d..46fcafd 100644
--- a/src/GMPShortener.php
+++ b/src/GMPShortener.php
@@ -5,24 +5,13 @@
 namespace Keiko\Uuid\Shortener;
 
 use Keiko\Uuid\Shortener\Exception\DictionaryException;
-use function array_flip;
-use function gmp_init;
-use function gmp_strval;
-use function preg_match;
-use function preg_quote;
-use function str_pad;
-use function str_replace;
-use function strrev;
-use function strtr;
-use function substr;
-use const STR_PAD_LEFT;
 
 /** @psalm-immutable */
 final class GMPShortener extends Shortener
 {
     /**
      * @var string[] a map of character replacements to be used when translating a number that is
-     *               in base(length(Dictionary)) (keys) to the dictionary characters (values).
+     *               in base(length(Dictionary)) (keys) to the dictionary characters (values)
      *
      * @psalm-var non-empty-array<non-empty-string, non-empty-string>
      */
@@ -35,48 +24,48 @@ public function __construct(private readonly Dictionary $dictionary)
         $replacements = [];
 
         foreach (range(0, $dictionary->length - 1) as $characterIndex) {
-            $replacements[gmp_strval(gmp_init((string) $characterIndex, 10), $dictionary->length)] = $dictionary->charsSet[$characterIndex];
+            $replacements[\gmp_strval(\gmp_init((string) $characterIndex, 10), $dictionary->length)] = $dictionary->charsSet[$characterIndex];
         }
 
         $this->baseReplacements = $replacements;
-        $this->allowedCharactersMatcher = '/^['. preg_quote($dictionary->charsSet, '/').']+$/';
+        $this->allowedCharactersMatcher = '/^['.\preg_quote($dictionary->charsSet, '/').']+$/';
     }
 
     public function reduce(string $uuid): string
     {
-        return strrev(strtr(
-            gmp_strval(gmp_init(str_replace('-', '', $uuid), 16), $this->dictionary->length),
+        return \strrev(\strtr(
+            \gmp_strval(\gmp_init(\str_replace('-', '', $uuid), 16), $this->dictionary->length),
             $this->baseReplacements
         ));
     }
 
     public function expand(string $shortUuid): string
     {
-        if (1 !== preg_match($this->allowedCharactersMatcher, $shortUuid)) {
+        if (1 !== \preg_match($this->allowedCharactersMatcher, $shortUuid)) {
             throw DictionaryException::indexOutOfBounds();
         }
 
-        $base16Uuid = str_pad(
-            gmp_strval(
-                gmp_init(
-                    strtr(strrev($shortUuid), array_flip($this->baseReplacements)),
+        $base16Uuid = \str_pad(
+            \gmp_strval(
+                \gmp_init(
+                    \strtr(\strrev($shortUuid), \array_flip($this->baseReplacements)),
                     $this->dictionary->length
                 ),
                 16
             ),
             32,
             '0',
-            STR_PAD_LEFT
+            \STR_PAD_LEFT
         );
 
-        return substr($base16Uuid,0, 8)
-            . '-'
-            . substr($base16Uuid, 8, 4)
-            . '-'
-            . substr($base16Uuid, 12, 4)
-            . '-'
-            . substr($base16Uuid, 16, 4)
-            . '-'
-            . substr($base16Uuid, 20, 12);
+        return \substr($base16Uuid, 0, 8)
+            .'-'
+            .\substr($base16Uuid, 8, 4)
+            .'-'
+            .\substr($base16Uuid, 12, 4)
+            .'-'
+            .\substr($base16Uuid, 16, 4)
+            .'-'
+            .\substr($base16Uuid, 20, 12);
     }
 }
diff --git a/src/Shortener.php b/src/Shortener.php
index dc2aa5d..e238960 100644
--- a/src/Shortener.php
+++ b/src/Shortener.php
@@ -9,28 +9,19 @@
 use Keiko\Uuid\Shortener\Exception\DictionaryException;
 use Keiko\Uuid\Shortener\Number\BigInt\Converter;
 use Keiko\Uuid\Shortener\Number\BigInt\ConverterInterface;
-use function extension_loaded;
-use function str_pad;
-use function str_split;
-use function strrev;
-use function substr;
 
 /** @psalm-immutable */
 class Shortener
 {
-    /**
-     * @param Dictionary         $dictionary
-     * @param ConverterInterface $converter
-     */
     public function __construct(
         private readonly Dictionary $dictionary,
         private readonly ConverterInterface $converter,
     ) {
     }
 
-    public static function make(Dictionary $dictionary) : self
+    public static function make(Dictionary $dictionary): self
     {
-        if (extension_loaded('gmp')) {
+        if (\extension_loaded('gmp')) {
             return new GMPShortener($dictionary);
         }
 
@@ -57,26 +48,26 @@ public function reduce(string $uuid): string
     public function expand(string $shortUuid): string
     {
         $number = BigInteger::zero();
-        foreach (str_split(strrev($shortUuid)) as $char) {
+        foreach (\str_split(\strrev($shortUuid)) as $char) {
             $number = $number
                 ->multipliedBy($this->dictionary->length)
                 ->plus(
-                    $this->dictionary->charIndexes[$char] ?? (static function () : string {
+                    $this->dictionary->charIndexes[$char] ?? (static function (): string {
                         throw DictionaryException::indexOutOfBounds();
                     })()
                 );
         }
 
-        $base16Uuid = str_pad($this->converter->toHex($number), 32, '0', STR_PAD_LEFT);
+        $base16Uuid = \str_pad($this->converter->toHex($number), 32, '0', STR_PAD_LEFT);
 
-        return substr($base16Uuid,0, 8)
-            . '-'
-            . substr($base16Uuid, 8, 4)
-            . '-'
-            . substr($base16Uuid, 12, 4)
-            . '-'
-            . substr($base16Uuid, 16, 4)
-            . '-'
-            . substr($base16Uuid, 20, 12);
+        return \substr($base16Uuid, 0, 8)
+            .'-'
+            .\substr($base16Uuid, 8, 4)
+            .'-'
+            .\substr($base16Uuid, 12, 4)
+            .'-'
+            .\substr($base16Uuid, 16, 4)
+            .'-'
+            .\substr($base16Uuid, 20, 12);
     }
 }
diff --git a/tests/DictionaryTest.php b/tests/DictionaryTest.php
index b63f3f4..6a245d5 100644
--- a/tests/DictionaryTest.php
+++ b/tests/DictionaryTest.php
@@ -26,14 +26,14 @@ public function testInitialDictionaryState(): void
         self::assertSame(57, $this->dictionary->length);
         self::assertSame(
             [
-                2   => 0,
-                3   => 1,
-                4   => 2,
-                5   => 3,
-                6   => 4,
-                7   => 5,
-                8   => 6,
-                9   => 7,
+                2 => 0,
+                3 => 1,
+                4 => 2,
+                5 => 3,
+                6 => 4,
+                7 => 5,
+                8 => 6,
+                9 => 7,
                 'A' => 8,
                 'B' => 9,
                 'C' => 10,
@@ -133,6 +133,7 @@ public function testThrowExceptonWhenGettingNonExistentCharsIndex(): void
 
         $this->dictionary->getCharIndex('Ć');
     }
+
     public function testCreateUnmistakableDictionary(): void
     {
         $dictionary = Dictionary::createUnmistakable();
diff --git a/tests/GMPShortenerTest.php b/tests/GMPShortenerTest.php
index a85d91f..2a81f17 100644
--- a/tests/GMPShortenerTest.php
+++ b/tests/GMPShortenerTest.php
@@ -10,7 +10,7 @@
 
 final class GMPShortenerTest extends ShortenerTestCase
 {
-    protected function shortener(Dictionary $dictionary = null) : Shortener
+    protected function shortener(Dictionary $dictionary = null): Shortener
     {
         return new GMPShortener($dictionary ?? Dictionary::createUnmistakable());
     }
diff --git a/tests/ShortenerTest.php b/tests/ShortenerTest.php
index b5a4de3..3d7e615 100644
--- a/tests/ShortenerTest.php
+++ b/tests/ShortenerTest.php
@@ -10,7 +10,7 @@
 
 final class ShortenerTest extends ShortenerTestCase
 {
-    protected function shortener(Dictionary $dictionary = null) : Shortener
+    protected function shortener(Dictionary $dictionary = null): Shortener
     {
         return new Shortener(
             $dictionary ?? Dictionary::createUnmistakable(),
diff --git a/tests/ShortenerTestCase.php b/tests/ShortenerTestCase.php
index 7114420..1d359b7 100644
--- a/tests/ShortenerTestCase.php
+++ b/tests/ShortenerTestCase.php
@@ -6,7 +6,6 @@
 
 use Keiko\Uuid\Shortener\Dictionary;
 use Keiko\Uuid\Shortener\Exception\DictionaryException;
-use Keiko\Uuid\Shortener\Number\BigInt\Converter;
 use Keiko\Uuid\Shortener\Shortener;
 use PHPUnit\Framework\TestCase;
 
@@ -74,12 +73,12 @@ public function uuidShortenedUnmistakable(): array
             ['806d0969-95b3-433b-976f-774611fdacbb', 'mavTAjNm4NVztDwh4gdSrQ'],
             ['0c5873e8-7fea-4570-9487-ffe96ec30257', 'LpGtrrQFCbneY2GtQiXDD4'],
             ['ffffffff-ffff-ffff-ffff-ffffffffffff', '5B8cwPMGnU6qLbRvo7qEZo'],
-            'One leading zero'                  => ['07fe2146-0a94-4a4a-9956-4cfd0d3560d9', 'rcPMmyWuaewoF8EM3JK5S3'],
-            '2 Leading zeroes'                  => ['00fe2146-0a94-4a4a-9956-4cfd0d3560d9', 'qgXznd8uPVbCJg5tB5r5C'],
+            'One leading zero' => ['07fe2146-0a94-4a4a-9956-4cfd0d3560d9', 'rcPMmyWuaewoF8EM3JK5S3'],
+            '2 Leading zeroes' => ['00fe2146-0a94-4a4a-9956-4cfd0d3560d9', 'qgXznd8uPVbCJg5tB5r5C'],
             'Smallest UUID, max leading zeroes' => ['00000000-0000-0000-0000-000000000001', '3'],
-            'Small UUID, many leading zeroes'   => ['00000000-0000-0000-0000-0000000000aa', 'z4'],
-            'Large UUID, many trailing zeroes'  => ['aa000000-0000-0000-0000-000000000000', 'ABitJoXBZDBeRvbiWuB5GY'],
-            'Random UUID with trailing zeroes'  => ['a7fe2146-0a94-4a4a-9956-4cfd0d3560d0', 'Fbab7rU5aCkhaybY3jphtX'],
+            'Small UUID, many leading zeroes' => ['00000000-0000-0000-0000-0000000000aa', 'z4'],
+            'Large UUID, many trailing zeroes' => ['aa000000-0000-0000-0000-000000000000', 'ABitJoXBZDBeRvbiWuB5GY'],
+            'Random UUID with trailing zeroes' => ['a7fe2146-0a94-4a4a-9956-4cfd0d3560d0', 'Fbab7rU5aCkhaybY3jphtX'],
         ];
     }
 }