diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 105bc90..96e4a08 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -7,6 +7,9 @@ on:
 permissions:
   contents: read
 
+env:
+  PHP_VERSION: '8.3'
+
 jobs:
   auto-review:
     name: Auto review
@@ -14,21 +17,18 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
-      - name: Use PHP 8.2
+      - name: Configure PHP
         uses: shivammathur/setup-php@v2
         with:
-          php-version: '8.2'
+          php-version: ${{ env.PHP_VERSION }}
 
       - name: Install dependencies
         run: composer update --no-progress --optimize-autoloader
 
-      - name: Run phpcs
-        run: composer phpcs
-
-      - name: Run phpmd
-        run: composer phpmd
+      - name: Run review
+        run: composer review
 
   tests:
     name: Tests
@@ -36,20 +36,15 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
-      - name: Use PHP 8.2
+      - name: Use PHP ${{ env.PHP_VERSION }}
         uses: shivammathur/setup-php@v2
         with:
-          php-version: '8.2'
+          php-version: ${{ env.PHP_VERSION }}
 
       - name: Install dependencies
         run: composer update --no-progress --optimize-autoloader
 
-      - name: Run unit tests
-        env:
-          XDEBUG_MODE: coverage
-        run: composer test
-
-      - name: Run mutation tests
-        run: composer test-mutation
+      - name: Run tests
+        run: composer tests
diff --git a/Makefile b/Makefile
index 1b3026e..3cfd101 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-DOCKER_RUN = docker run --rm -it --net=host -v ${PWD}:/app -w /app gustavofreze/php:8.2
+DOCKER_RUN = docker run --rm -it --net=host -v ${PWD}:/app -w /app gustavofreze/php:8.3
 
 .PHONY: configure test test-file test-no-coverage review show-reports clean
 
diff --git a/composer.json b/composer.json
index 4582ab4..6fc3550 100644
--- a/composer.json
+++ b/composer.json
@@ -40,18 +40,18 @@
         }
     },
     "require": {
-        "php": "^8.2",
-        "ext-gmp": "*"
+        "php": "^8.3",
+        "ext-bcmath": "*"
     },
     "require-dev": {
         "phpmd/phpmd": "^2.15",
         "phpunit/phpunit": "^11",
         "phpstan/phpstan": "^1",
         "infection/infection": "^0.29",
-        "squizlabs/php_codesniffer": "^3.10"
+        "squizlabs/php_codesniffer": "^3.11"
     },
     "suggest": {
-        "ext-gmp": "Enables faster math with arbitrary-precision integers using GMP."
+        "ext-bcmath": "Enables the extension which is an interface to the GNU implementation as a Basic Calculator utility library."
     },
     "scripts": {
         "phpcs": "phpcs --standard=PSR12 --extensions=php ./src",
@@ -60,7 +60,6 @@
         "test": "phpunit --log-junit=report/coverage/junit.xml --coverage-xml=report/coverage/coverage-xml --coverage-html=report/coverage/coverage-html tests",
         "test-mutation": "infection --only-covered --logger-html=report/coverage/mutation-report.html --coverage=report/coverage --min-msi=100 --min-covered-msi=100 --threads=4",
         "test-no-coverage": "phpunit --no-coverage",
-        "test-mutation-no-coverage": "infection --only-covered --min-msi=100 --threads=4",
         "review": [
             "@phpcs",
             "@phpmd",
@@ -71,8 +70,7 @@
             "@test-mutation"
         ],
         "tests-no-coverage": [
-            "@test-no-coverage",
-            "@test-mutation-no-coverage"
+            "@test-no-coverage"
         ]
     }
 }
diff --git a/infection.json.dist b/infection.json.dist
index 0bdd7f1..72bef1b 100644
--- a/infection.json.dist
+++ b/infection.json.dist
@@ -1,5 +1,5 @@
 {
-    "timeout": 10,
+    "timeout": 30,
     "testFramework": "phpunit",
     "tmpDir": "report/infection/",
     "source": {
@@ -13,7 +13,12 @@
     },
     "mutators": {
         "@default": true,
+        "BCMath": false,
+        "CastInt": false,
+        "Increment": false,
+        "GreaterThan": false,
         "UnwrapSubstr": false,
+        "UnwrapStrToLower": false,
         "LogicalAndNegation": false,
         "LogicalAndAllSubExprNegation": false
     },
diff --git a/src/Base62.php b/src/Base62.php
index 2070ddd..1b24e24 100644
--- a/src/Base62.php
+++ b/src/Base62.php
@@ -4,15 +4,16 @@
 
 namespace TinyBlocks\Encoder;
 
+use TinyBlocks\Encoder\Internal\Decimal;
 use TinyBlocks\Encoder\Internal\Exceptions\InvalidDecoding;
 use TinyBlocks\Encoder\Internal\Hexadecimal;
 
 final readonly class Base62 implements Encoder
 {
-    private const BASE62_RADIX = 62;
-    private const BASE62_ALPHABET = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
-    private const BASE62_CHARACTER_LENGTH = 1;
-    private const BASE62_HEXADECIMAL_RADIX = 16;
+    public const int BASE62_RADIX = 62;
+    private const int BASE62_CHARACTER_LENGTH = 1;
+
+    private const string BASE62_ALPHABET = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
 
     private function __construct(private string $value)
     {
@@ -25,18 +26,18 @@ public static function from(string $value): Encoder
 
     public function encode(): string
     {
-        $hexadecimal = Hexadecimal::fromBinary(binary: $this->value);
-        $bytes = $hexadecimal->removeLeadingZeroBytes();
+        $hexadecimal = Hexadecimal::fromBinary(binary: $this->value, alphabet: self::BASE62_ALPHABET);
+        $hexadecimal = $hexadecimal->removeLeadingZeroBytes();
 
-        $base62 = str_repeat(self::BASE62_ALPHABET[0], $bytes);
+        $base62 = str_repeat(self::BASE62_ALPHABET[0], $hexadecimal->getBytes());
 
         if ($hexadecimal->isEmpty()) {
             return $base62;
         }
 
-        $number = $hexadecimal->toGmpInit(base: self::BASE62_HEXADECIMAL_RADIX);
+        $base62Value = $hexadecimal->toBase(base: self::BASE62_RADIX);
 
-        return sprintf('%s%s', $base62, gmp_strval($number, self::BASE62_RADIX));
+        return sprintf('%s%s', $base62, $base62Value);
     }
 
     public function decode(): string
@@ -57,16 +58,13 @@ public function decode(): string
             return str_repeat("\x00", $bytes);
         }
 
-        $number = gmp_init($value, self::BASE62_RADIX);
-        $hexadecimal = Hexadecimal::fromGmp(number: $number, base: self::BASE62_HEXADECIMAL_RADIX);
-        $hexadecimal->padLeft();
-
-        $binary = hex2bin(sprintf('%s%s', str_repeat('00', $bytes), $hexadecimal->toString()));
+        $decimal = Decimal::fromBase62(number: $value, alphabet: self::BASE62_ALPHABET);
+        $hexadecimal = Hexadecimal::from(value: $decimal->toHexadecimal())
+            ->fillWithZeroIfNecessary()
+            ->toString();
 
-        if (!is_string($binary)) {
-            throw new InvalidDecoding(value: $this->value);
-        }
+        $binary = hex2bin($hexadecimal);
 
-        return $binary;
+        return sprintf('%s%s', str_repeat("\x00", $bytes), $binary);
     }
 }
diff --git a/src/Internal/Decimal.php b/src/Internal/Decimal.php
new file mode 100644
index 0000000..50dceee
--- /dev/null
+++ b/src/Internal/Decimal.php
@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+namespace TinyBlocks\Encoder\Internal;
+
+use TinyBlocks\Encoder\Base62;
+
+final readonly class Decimal
+{
+    private function __construct(private string $value)
+    {
+    }
+
+    public static function fromBase62(string $number, string $alphabet): Decimal
+    {
+        $value = '0';
+        $length = strlen($number);
+
+        for ($index = 0; $index < $length; $index++) {
+            $digit = strpos($alphabet, $number[$index]);
+            $value = bcmul($value, (string)Base62::BASE62_RADIX);
+            $value = bcadd($value, (string)$digit);
+        }
+
+        return new Decimal(value: $value);
+    }
+
+    public function toHexadecimal(): string
+    {
+        $value = $this->value;
+        $hexadecimalValue = '';
+
+        while (bccomp($value, '0') > 0) {
+            $remainder = bcmod($value, Hexadecimal::HEXADECIMAL_RADIX);
+            $hexadecimalValue = sprintf('%s%s', Hexadecimal::HEXADECIMAL_ALPHABET[(int)$remainder], $hexadecimalValue);
+            $value = bcdiv($value, Hexadecimal::HEXADECIMAL_RADIX);
+        }
+
+        return $hexadecimalValue;
+    }
+}
diff --git a/src/Internal/Exceptions/InvalidDecoding.php b/src/Internal/Exceptions/InvalidDecoding.php
index d5e1b48..f53735e 100644
--- a/src/Internal/Exceptions/InvalidDecoding.php
+++ b/src/Internal/Exceptions/InvalidDecoding.php
@@ -11,6 +11,7 @@ final class InvalidDecoding extends RuntimeException
     public function __construct(private readonly string $value)
     {
         $template = 'The value <%s> could not be decoded.';
+
         parent::__construct(message: sprintf($template, $this->value));
     }
 }
diff --git a/src/Internal/Hexadecimal.php b/src/Internal/Hexadecimal.php
index f06e424..1b126f4 100644
--- a/src/Internal/Hexadecimal.php
+++ b/src/Internal/Hexadecimal.php
@@ -4,60 +4,86 @@
 
 namespace TinyBlocks\Encoder\Internal;
 
-use GMP;
-
-final class Hexadecimal
+final readonly class Hexadecimal
 {
-    private const HEXADECIMAL_BYTE_LENGTH = 2;
+    private const int DEFAULT_BYTE_COUNT = 0;
+    private const int HEXADECIMAL_BYTE_LENGTH = 2;
 
-    private string $value;
+    public const string HEXADECIMAL_RADIX = '16';
+    public const string HEXADECIMAL_ALPHABET = '0123456789abcdef';
 
-    private function __construct(string $value)
-    {
-        $this->value = $value;
+    private function __construct(
+        private string $value,
+        private string $alphabet,
+        private int $bytes = self::DEFAULT_BYTE_COUNT
+    ) {
     }
 
-    public static function fromGmp(GMP $number, int $base): Hexadecimal
+    public static function from(string $value): Hexadecimal
     {
-        return new Hexadecimal(value: gmp_strval($number, $base));
+        return new Hexadecimal(value: $value, alphabet: self::HEXADECIMAL_ALPHABET);
     }
 
-    public static function fromBinary(string $binary): Hexadecimal
+    public static function fromBinary(string $binary, string $alphabet): Hexadecimal
     {
-        return new Hexadecimal(value: bin2hex($binary));
+        return new Hexadecimal(value: bin2hex($binary), alphabet: $alphabet);
     }
 
-    public function isEmpty(): bool
+    public function removeLeadingZeroBytes(): Hexadecimal
     {
-        return empty($this->value);
+        $bytes = 0;
+        $newValue = $this->value;
+
+        while (str_starts_with($newValue, '00')) {
+            $bytes++;
+            $newValue = substr($newValue, self::HEXADECIMAL_BYTE_LENGTH);
+        }
+
+        return new Hexadecimal(value: $newValue, alphabet: $this->alphabet, bytes: $bytes);
     }
 
-    public function padLeft(): void
+    public function fillWithZeroIfNecessary(): Hexadecimal
     {
-        if (strlen($this->value) % 2 !== 0) {
-            $this->value = sprintf('0%s', $this->value);
-        }
+        $newValue = strlen($this->value) % 2 !== 0 ? sprintf('0%s', $this->value) : $this->value;
+
+        return new Hexadecimal(value: $newValue, alphabet: $this->alphabet, bytes: $this->bytes);
     }
 
-    public function toString(): string
+    public function getBytes(): int
     {
-        return $this->value;
+        return $this->bytes;
     }
 
-    public function toGmpInit(int $base): GMP
+    public function isEmpty(): bool
     {
-        return gmp_init($this->value, $base);
+        return empty($this->value);
     }
 
-    public function removeLeadingZeroBytes(): int
+    public function toBase(int $base): string
     {
-        $bytes = 0;
+        $length = strlen($this->value);
+        $decimalValue = '0';
 
-        while (str_starts_with($this->value, '00')) {
-            $bytes++;
-            $this->value = substr($this->value, self::HEXADECIMAL_BYTE_LENGTH);
+        for ($index = 0; $index < $length; $index++) {
+            $digit = strpos(self::HEXADECIMAL_ALPHABET, strtolower($this->value[$index]));
+            $decimalValue = bcmul($decimalValue, self::HEXADECIMAL_RADIX);
+            $decimalValue = bcadd($decimalValue, (string)$digit);
+        }
+
+        $digits = $this->alphabet;
+        $result = '';
+
+        while (bccomp($decimalValue, '0') > 0) {
+            $remainder = bcmod($decimalValue, (string)$base);
+            $result = sprintf('%s%s', $digits[(int)$remainder], $result);
+            $decimalValue = bcdiv($decimalValue, (string)$base);
         }
 
-        return $bytes;
+        return $result ?: '0';
+    }
+
+    public function toString(): string
+    {
+        return $this->value;
     }
 }
diff --git a/tests/Base62Test.php b/tests/Base62Test.php
index 3d175be..4ead139 100644
--- a/tests/Base62Test.php
+++ b/tests/Base62Test.php
@@ -77,29 +77,32 @@ public function testEncodeAndDecodeWithLeadingZeroBytes(string $value): void
     public static function providerForTestEncode(): array
     {
         return [
-            'hello world' => ['value' => 'Hello world!', 'expected' => 'T8dgcjRGuYUueWht'],
-            'empty string' => ['value' => '', 'expected' => ''],
-            'numeric string' => ['value' => '1234567890', 'expected' => '1A0afZkibIAR2O'],
-            'special characters' => ['value' => '@#$%^&*()', 'expected' => 'MjehbVgJedVR']
+            'Hello world'        => ['value' => 'Hello world!', 'expected' => 'T8dgcjRGuYUueWht'],
+            'Empty string'       => ['value' => '', 'expected' => ''],
+            'Numeric string'     => ['value' => '1234567890', 'expected' => '1A0afZkibIAR2O'],
+            'Special characters' => ['value' => '@#$%^&*()', 'expected' => 'MjehbVgJedVR']
         ];
     }
 
     public static function providerForTestDecode(): array
     {
         return [
-            'empty string' => ['value' => '', 'expected' => ''],
-            'hello world' => ['value' => 'T8dgcjRGuYUueWht', 'expected' => 'Hello world!'],
-            'numeric string' => ['value' => '1A0afZkibIAR2O', 'expected' => '1234567890'],
-            'special characters' => ['value' => 'MjehbVgJedVR', 'expected' => '@#$%^&*()']
+            'Zero value'         => ['value' => '0', 'expected' => ''],
+            'Empty string'       => ['value' => '', 'expected' => ''],
+            'Hello world'        => ['value' => 'T8dgcjRGuYUueWht', 'expected' => 'Hello world!'],
+            'Leading zeros'      => ['value' => '000001', 'expected' => hex2bin('000000000001')],
+            'Numeric string'     => ['value' => '1A0afZkibIAR2O', 'expected' => '1234567890'],
+            'Single character'   => ['value' => '1', 'expected' => "\001"],
+            'Special characters' => ['value' => 'MjehbVgJedVR', 'expected' => '@#$%^&*()']
         ];
     }
 
     public static function providerForTestEncodeAndDecodeWithLeadingZeroBytes(): array
     {
         return [
-            'leading zero bytes 01' => ['value' => '001jlt60MnKnB9ECKRt4gl'],
-            'leading zero bytes 02' => ['value' => hex2bin('07d8e31da269bf28')],
-            'leading zero bytes 03' => ['value' => hex2bin('0000010203040506')]
+            'Leading zero bytes 01' => ['value' => '001jlt60MnKnB9ECKRt4gl'],
+            'Leading zero bytes 02' => ['value' => hex2bin('07d8e31da269bf28')],
+            'Leading zero bytes 03' => ['value' => hex2bin('0000010203040506')]
         ];
     }
 }