diff --git a/src/Pin/InputPin.php b/src/Pin/InputPin.php
index 8d81460..b93c74e 100644
--- a/src/Pin/InputPin.php
+++ b/src/Pin/InputPin.php
@@ -16,9 +16,6 @@ final class InputPin extends Pin implements InputPinInterface
      */
     public function __construct(FileSystemInterface $fileSystem, $number)
     {
-        $this->fileSystem = $fileSystem;
-        $this->number = $number;
-
         parent::__construct($fileSystem, $number);
 
         $this->setDirection(self::DIRECTION_IN);
diff --git a/src/Pin/OutputPin.php b/src/Pin/OutputPin.php
index 4ab3fad..5ce0dbb 100644
--- a/src/Pin/OutputPin.php
+++ b/src/Pin/OutputPin.php
@@ -14,9 +14,6 @@ final class OutputPin extends Pin implements OutputPinInterface
      */
     public function __construct(FileSystemInterface $fileSystem, $number)
     {
-        $this->fileSystem = $fileSystem;
-        $this->number = $number;
-
         parent::__construct($fileSystem, $number);
 
         $this->setDirection(self::DIRECTION_OUT);
diff --git a/src/Pin/Pin.php b/src/Pin/Pin.php
index bd149c1..f534415 100644
--- a/src/Pin/Pin.php
+++ b/src/Pin/Pin.php
@@ -22,8 +22,8 @@ abstract class Pin implements PinInterface
     const DIRECTION_IN = 'in';
     const DIRECTION_OUT = 'out';
 
-    private $fileSystem;
-    private $number;
+    protected $fileSystem;
+    protected $number;
 
     /**
      * Constructor.