diff --git a/composer.json b/composer.json
index 017c52e..02361b8 100644
--- a/composer.json
+++ b/composer.json
@@ -46,7 +46,7 @@
     },
     "require-dev": {
         "ext-xdebug": "*",
-        "aplus/coding-standard": "^2.0",
+        "aplus/coding-standard": "^2.8",
         "ergebnis/composer-normalize": "^2.25",
         "jetbrains/phpstorm-attributes": "^1.0",
         "phpmd/phpmd": "^2.13",
diff --git a/src/Cache.php b/src/Cache.php
index c73cbd9..c7f1957 100644
--- a/src/Cache.php
+++ b/src/Cache.php
@@ -69,9 +69,9 @@ abstract class Cache
     public function __construct(
         #[SensitiveParameter]
         ?array $configs = [],
-        string $prefix = null,
+        ?string $prefix = null,
         Serializer | string $serializer = Serializer::PHP,
-        Logger $logger = null
+        ?Logger $logger = null
     ) {
         $this->prefix = $prefix;
         if (\is_string($serializer)) {
@@ -179,7 +179,7 @@ public function getMulti(array $keys) : array
      *
      * @return bool TRUE if the item was set, FALSE if fail to set
      */
-    abstract public function set(string $key, mixed $value, int $ttl = null) : bool;
+    abstract public function set(string $key, mixed $value, ?int $ttl = null) : bool;
 
     /**
      * Sets multi items to the cache storage.
@@ -189,7 +189,7 @@ abstract public function set(string $key, mixed $value, int $ttl = null) : bool;
      *
      * @return array<string,bool> associative array with key names and respective set status
      */
-    public function setMulti(array $data, int $ttl = null) : array
+    public function setMulti(array $data, ?int $ttl = null) : array
     {
         foreach ($data as $key => &$value) {
             $value = $this->set($key, $value, $ttl);
@@ -238,7 +238,7 @@ abstract public function flush() : bool;
      *
      * @return int The current item value
      */
-    public function increment(string $key, int $offset = 1, int $ttl = null) : int
+    public function increment(string $key, int $offset = 1, ?int $ttl = null) : int
     {
         $offset = (int) \abs($offset);
         $value = (int) $this->get($key);
@@ -256,7 +256,7 @@ public function increment(string $key, int $offset = 1, int $ttl = null) : int
      *
      * @return int The current item value
      */
-    public function decrement(string $key, int $offset = 1, int $ttl = null) : int
+    public function decrement(string $key, int $offset = 1, ?int $ttl = null) : int
     {
         $offset = (int) \abs($offset);
         $value = (int) $this->get($key);
diff --git a/src/FilesCache.php b/src/FilesCache.php
index 716703c..03d5a90 100644
--- a/src/FilesCache.php
+++ b/src/FilesCache.php
@@ -133,7 +133,7 @@ protected function createSubDirectory(string $filepath) : void
         }
     }
 
-    public function set(string $key, mixed $value, int $ttl = null) : bool
+    public function set(string $key, mixed $value, ?int $ttl = null) : bool
     {
         if (isset($this->debugCollector)) {
             $start = \microtime(true);
@@ -148,7 +148,7 @@ public function set(string $key, mixed $value, int $ttl = null) : bool
         return $this->setValue($key, $value, $ttl);
     }
 
-    public function setValue(string $key, mixed $value, int $ttl = null) : bool
+    public function setValue(string $key, mixed $value, ?int $ttl = null) : bool
     {
         $filepath = $this->renderFilepath($key);
         $this->createSubDirectory($filepath);
diff --git a/src/MemcachedCache.php b/src/MemcachedCache.php
index 9c71391..c8e88c4 100644
--- a/src/MemcachedCache.php
+++ b/src/MemcachedCache.php
@@ -110,7 +110,7 @@ protected function getValue(string $key) : mixed
             : $key;
     }
 
-    public function set(string $key, mixed $value, int $ttl = null) : bool
+    public function set(string $key, mixed $value, ?int $ttl = null) : bool
     {
         if (isset($this->debugCollector)) {
             $start = \microtime(true);
diff --git a/src/RedisCache.php b/src/RedisCache.php
index 840ff7d..e7403fe 100644
--- a/src/RedisCache.php
+++ b/src/RedisCache.php
@@ -107,7 +107,7 @@ protected function getValue(string $key) : mixed
         return $this->unserialize($value);
     }
 
-    public function set(string $key, mixed $value, int $ttl = null) : bool
+    public function set(string $key, mixed $value, ?int $ttl = null) : bool
     {
         if (isset($this->debugCollector)) {
             $start = \microtime(true);
diff --git a/tests/CacheMock.php b/tests/CacheMock.php
index a847fa2..36028cc 100644
--- a/tests/CacheMock.php
+++ b/tests/CacheMock.php
@@ -23,7 +23,7 @@ public function get(string $key) : mixed
         return 1;
     }
 
-    public function set(string $key, mixed $value, int $ttl = null) : bool
+    public function set(string $key, mixed $value, ?int $ttl = null) : bool
     {
         return true;
     }