diff --git a/src/Connection.php b/src/Connection.php
index 852d12c..c067acd 100644
--- a/src/Connection.php
+++ b/src/Connection.php
@@ -32,7 +32,7 @@ public function __construct(
         string $host,
         int $port = Socket::DEFAULT_PORT,
         array $options = [],
-        \Closure $createSocket = null
+        ?\Closure $createSocket = null
     ) {
         if (isset($createSocket)) {
             $this->socket = $createSocket($host, $port, $options);
diff --git a/src/Connection/Socket.php b/src/Connection/Socket.php
index dc43406..fd2c0b1 100644
--- a/src/Connection/Socket.php
+++ b/src/Connection/Socket.php
@@ -79,7 +79,7 @@ public function write(string $data): void
         }
     }
 
-    public function read(int $length = null): string
+    public function read(?int $length = null): string
     {
         $this->connect();
 
diff --git a/src/Exception/BuriedException.php b/src/Exception/BuriedException.php
index f16f359..d35f0b0 100644
--- a/src/Exception/BuriedException.php
+++ b/src/Exception/BuriedException.php
@@ -13,7 +13,7 @@ public static function create(int $jobId): self
 
     private int $jobId;
 
-    public function __construct(int $jobId, string $message, int $code = 0, \Exception $previous = null)
+    public function __construct(int $jobId, string $message, int $code = 0, ?\Exception $previous = null)
     {
         $this->jobId = $jobId;
         parent::__construct($message, $code, $previous);