diff --git a/.gitignore b/.gitignore
index 5d13a24..f82edd4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 composer.lock
 vendor
 .idea
+.php-cs-fixer.cache
diff --git a/.travis.yml b/.travis.yml
index ce14233..190c784 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -9,9 +9,5 @@ script:
 matrix:
   fast_finish: true
   include:
-    - php: 7.0
-    - php: 7.1
-    - php: 7.2
-    - php: 7.3
-    - php: 7.4
     - php: 8.0
+    - php: 8.1
diff --git a/composer.json b/composer.json
index e7652e3..9d04ca5 100644
--- a/composer.json
+++ b/composer.json
@@ -10,12 +10,14 @@
     }
   ],
   "require": {
-    "php": ">=7.0",
-    "ext-mbstring": "*",
+    "php": ">=8.0",
+    "ext-zlib": "*",
     "predis/predis": "^1.1.1"
   },
   "require-dev": {
-    "phpunit/phpunit": "^6.2"
+    "phpunit/phpunit": "^9.5",
+    "friendsofphp/php-cs-fixer": "^3.8",
+    "phpstan/phpstan": "^1.5"
   },
   "autoload": {
     "psr-4": {
@@ -26,5 +28,10 @@
     "psr-4": {
       "B1rdex\\PredisCompressible\\Tests\\": "tests/"
     }
+  },
+  "scripts": {
+    "test": "vendor/bin/phpunit tests/",
+    "fix-cs": "vendor/bin/php-cs-fixer fix --rules=@PSR12:risky,@PHP80Migration:risky,@PHPUnit84Migration:risky --allow-risky=yes .",
+    "sca": "vendor/bin/phpstan --memory-limit=-1 analyse --level=max src/ tests/"
   }
 }
diff --git a/src/Command/ArgumentsCompressibleCommandInterface.php b/src/Command/ArgumentsCompressibleCommandInterface.php
index aa60b64..9088006 100644
--- a/src/Command/ArgumentsCompressibleCommandInterface.php
+++ b/src/Command/ArgumentsCompressibleCommandInterface.php
@@ -6,5 +6,10 @@
 
 interface ArgumentsCompressibleCommandInterface extends CompressibleCommandInterface
 {
+	/**
+	 * @param list<mixed> $arguments
+	 *
+	 * @return list<mixed>
+	 */
     public function compressArguments(array $arguments): array;
 }
diff --git a/src/Command/CompressArgumentsHelperTrait.php b/src/Command/CompressArgumentsHelperTrait.php
index 145643b..0b63a6c 100644
--- a/src/Command/CompressArgumentsHelperTrait.php
+++ b/src/Command/CompressArgumentsHelperTrait.php
@@ -5,15 +5,16 @@
 namespace B1rdex\PredisCompressible\Command;
 
 use B1rdex\PredisCompressible\Compressor\CompressorException;
+use B1rdex\PredisCompressible\Compressor\CompressorInterface;
 
 trait CompressArgumentsHelperTrait
 {
-    /**
-     * @var \B1rdex\PredisCompressible\Compressor\CompressorInterface
-     */
-    protected $compressor;
+    protected CompressorInterface $compressor;
 
-    protected function compressArgument(array &$arguments, int $position)
+	/**
+	 * @param list<mixed> $arguments
+	 */
+    protected function compressArgument(array &$arguments, int $position): void
     {
         $content = $arguments[$position];
 
diff --git a/src/Command/CompressibleCommandInterface.php b/src/Command/CompressibleCommandInterface.php
index ea38b3b..23325ef 100644
--- a/src/Command/CompressibleCommandInterface.php
+++ b/src/Command/CompressibleCommandInterface.php
@@ -8,5 +8,5 @@
 
 interface CompressibleCommandInterface
 {
-    public function setCompressor(CompressorInterface $compressor);
+    public function setCompressor(CompressorInterface $compressor): void;
 }
diff --git a/src/Command/CompressibleCommandTrait.php b/src/Command/CompressibleCommandTrait.php
index 7c099c0..b9f0713 100644
--- a/src/Command/CompressibleCommandTrait.php
+++ b/src/Command/CompressibleCommandTrait.php
@@ -8,12 +8,9 @@
 
 trait CompressibleCommandTrait
 {
-    /**
-     * @var \B1rdex\PredisCompressible\Compressor\CompressorInterface
-     */
-    protected $compressor;
+    protected CompressorInterface $compressor;
 
-    public function setCompressor(CompressorInterface $compressor)
+    public function setCompressor(CompressorInterface $compressor): void
     {
         $this->compressor = $compressor;
     }
diff --git a/src/Command/StringGetMultiple.php b/src/Command/StringGetMultiple.php
index a9622e2..8625018 100644
--- a/src/Command/StringGetMultiple.php
+++ b/src/Command/StringGetMultiple.php
@@ -10,23 +10,25 @@ class StringGetMultiple extends BaseStringGetMultiple implements CompressibleCom
 {
     use CompressibleCommandTrait;
 
+	/**
+	 * @param list<string>|string $data
+	 */
     public function parseResponse($data)
     {
         if (is_array($data)) {
-            return array_map(function($item) {
-                return $this->decompress($item);
-            }, $data);
+            return array_map(fn($item) => $this->decompress($item), $data);
         }
 
         return $this->decompress($data);
     }
 
-    private function decompress(string $data = null)
-    {
+    private function decompress(?string $data): ?string
+	{
         if (!$this->compressor->isCompressed($data)) {
             return $data;
         }
 
+		/** @var string $data */
         return $this->compressor->decompress($data);
     }
 }
diff --git a/src/CompressProcessor.php b/src/CompressProcessor.php
index e623d69..05325a8 100644
--- a/src/CompressProcessor.php
+++ b/src/CompressProcessor.php
@@ -12,14 +12,11 @@
 
 class CompressProcessor implements ProcessorInterface
 {
-    private $compressor;
-
-    public function __construct(CompressorInterface $compressor)
+    public function __construct(private CompressorInterface $compressor)
     {
-        $this->compressor = $compressor;
     }
 
-    public function process(CommandInterface $command)
+    public function process(CommandInterface $command): void
     {
         if ($command instanceof CompressibleCommandInterface) {
             $command->setCompressor($this->compressor);
diff --git a/src/Compressor/CompressorException.php b/src/Compressor/CompressorException.php
index d9de238..5678511 100644
--- a/src/Compressor/CompressorException.php
+++ b/src/Compressor/CompressorException.php
@@ -4,6 +4,6 @@
 
 namespace B1rdex\PredisCompressible\Compressor;
 
-interface CompressorException
+interface CompressorException extends \Throwable
 {
 }
diff --git a/src/Compressor/CompressorInterface.php b/src/Compressor/CompressorInterface.php
index decff90..2a806c4 100644
--- a/src/Compressor/CompressorInterface.php
+++ b/src/Compressor/CompressorInterface.php
@@ -7,31 +7,21 @@
 interface CompressorInterface
 {
     /**
-     * Returns compressed string or original string if its size is less than threshold
+     * Returns a compressed string or original data if its not compressible
      *
-     * @param mixed $data
-     *
-     * @return string|mixed Gzip string or original data
+     * @return string|mixed A compressed string or original data
      */
-    public function compress($data);
+    public function compress(mixed $data): mixed;
 
     /**
-     * Checks if $data is gzipped string
-     *
-     * @param mixed $data
-     *
-     * @return bool
+     * Checks if $data is a compressed string
      */
-    public function isCompressed($data): bool;
+    public function isCompressed(mixed $data): bool;
 
     /**
      * Returns original string from compressed $data
      *
-     * @param string $data
-     *
-     * @return string
-     *
-     * @throws \B1rdex\PredisCompressible\Compressor\CompressorException
+     * @throws CompressorException
      */
     public function decompress(string $data): string;
 }
diff --git a/src/Compressor/ConditionalCompressorWrapper.php b/src/Compressor/ConditionalCompressorWrapper.php
index 2cac7ce..e42f3f0 100644
--- a/src/Compressor/ConditionalCompressorWrapper.php
+++ b/src/Compressor/ConditionalCompressorWrapper.php
@@ -6,25 +6,11 @@
 
 class ConditionalCompressorWrapper implements CompressorInterface
 {
-    /**
-     * @var int
-     */
-    private $bytesThreshold;
-    /**
-     * @var \B1rdex\PredisCompressible\Compressor\CompressorInterface
-     */
-    private $compressor;
-
-    public function __construct(int $bytesThreshold, CompressorInterface $compressor)
+	public function __construct(private int $bytesThreshold, private CompressorInterface $compressor)
     {
-        $this->bytesThreshold = $bytesThreshold;
-        $this->compressor = $compressor;
-    }
+	}
 
-    /**
-     * {@inheritdoc}
-     */
-    public function compress($data)
+    public function compress(mixed $data): mixed
     {
         if ($this->shouldCompress($data)) {
             return $this->compressor->compress($data);
@@ -33,26 +19,20 @@ public function compress($data)
         return $data;
     }
 
-    private function shouldCompress($data): bool
+    private function shouldCompress(mixed $data): bool
     {
         if (!\is_string($data)) {
             return false;
         }
 
-        return \mb_strlen($data, 'US-ASCII') > $this->bytesThreshold;
+        return strlen($data) > $this->bytesThreshold;
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function isCompressed($data): bool
+    public function isCompressed(mixed $data): bool
     {
         return $this->compressor->isCompressed($data);
     }
 
-    /**
-     * {@inheritdoc}
-     */
     public function decompress(string $data): string
     {
         return $this->compressor->decompress($data);
diff --git a/src/Compressor/GzipCompressor.php b/src/Compressor/GzipCompressor.php
index a88bce1..556178e 100644
--- a/src/Compressor/GzipCompressor.php
+++ b/src/Compressor/GzipCompressor.php
@@ -8,12 +8,13 @@
 
 class GzipCompressor implements CompressorInterface
 {
-    /**
-     * {@inheritdoc}
-     */
-    public function compress($data)
-    {
-        $compressed = @\gzencode($data);
+    public function compress(mixed $data): mixed
+	{
+		if (!\is_string($data)) {
+			return $data;
+		}
+
+        $compressed = @gzencode($data);
         if ($compressed === false) {
             throw new class('Compression failed') extends RuntimeException implements CompressorException {};
         }
@@ -21,21 +22,15 @@ public function compress($data)
         return $compressed;
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function isCompressed($data): bool
+    public function isCompressed(mixed $data): bool
     {
         if (!\is_string($data)) {
             return false;
         }
 
-        return 0 === \mb_strpos($data, "\x1f" . "\x8b" . "\x08", 0, 'US-ASCII');
+        return str_starts_with($data, "\x1f" . "\x8b" . "\x08");
     }
 
-    /**
-     * {@inheritdoc}
-     */
     public function decompress(string $data): string
     {
         $decompressed = @\gzdecode($data);
diff --git a/tests/ClientTest.php b/tests/ClientTest.php
index 5978f1d..11f32dd 100644
--- a/tests/ClientTest.php
+++ b/tests/ClientTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace Sp\Tests\PredisCompress;
+namespace B1rdex\PredisCompressible\Tests;
 
 use B1rdex\PredisCompressible\Command\StringGet;
 use B1rdex\PredisCompressible\Command\StringGetMultiple;
@@ -24,7 +24,7 @@ class ClientTest extends TestCase
     /**
      * @test
      */
-    public function it_should_work()
+    public function it_should_work(): void
     {
         $sut = $this->getCompressedClient();
 
@@ -74,9 +74,16 @@ private function getCompressedClient(): Client
         $sut->connect();
         $this->assertTrue($sut->isConnected());
 
+		// clear redis db before running the tests
+		$sut->flushdb();
+
         return $sut;
     }
 
+	/**
+	 * @see \Predis\Client::createConnection()
+	 * @return array<mixed>
+	 */
     private function getConnectionParameters(): array
     {
         return [];
@@ -90,7 +97,7 @@ private function getOriginalClient(): OriginalClient
     /**
      * @test
      */
-    public function it_should_allow_setex()
+    public function it_should_allow_setex(): void
     {
         $sut = $this->getCompressedClient();
 
@@ -112,7 +119,7 @@ public function it_should_allow_setex()
     /**
      * @test
      */
-    public function it_should_allow_setnx()
+    public function it_should_allow_setnx(): void
     {
         $sut = $this->getCompressedClient();
 
@@ -134,7 +141,7 @@ public function it_should_allow_setnx()
     /**
      * @test
      */
-    public function it_should_not_throw_on_any_scalar_types()
+    public function it_should_not_throw_on_any_scalar_types(): void
     {
         $sut = $this->getCompressedClient();
 
@@ -149,7 +156,7 @@ public function it_should_not_throw_on_any_scalar_types()
     /**
      * @test
      */
-    public function it_should_allow_mget()
+    public function it_should_allow_mget(): void
     {
         $sut = $this->getCompressedClient();
 
@@ -173,7 +180,7 @@ public function it_should_allow_mget()
     /**
      * @test
      */
-    public function it_should_allow_mset()
+    public function it_should_allow_mset(): void
     {
         $sut = $this->getCompressedClient();
 
diff --git a/tests/ConditionalCompressorWrapperTest.php b/tests/ConditionalCompressorWrapperTest.php
index 2a77591..d96f24b 100644
--- a/tests/ConditionalCompressorWrapperTest.php
+++ b/tests/ConditionalCompressorWrapperTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace Sp\Tests\PredisCompress;
+namespace B1rdex\PredisCompressible;
 
 use B1rdex\PredisCompressible\Compressor\CompressorException;
 use B1rdex\PredisCompressible\Compressor\ConditionalCompressorWrapper;
@@ -17,13 +17,14 @@ class ConditionalCompressorWrapperTest extends TestCase
     /**
      * @test
      */
-    public function it_should_work()
+    public function it_should_work(): void
     {
         $sut = new ConditionalCompressorWrapper(5, new GzipCompressor());
 
         $data = 'some text string';
 
         $compressed = $sut->compress($data);
+		assert(is_string($compressed));
         $this->assertStringStartsNotWith($data, $compressed);
 
         $decompressed = $sut->decompress($compressed);