Typehint fail in Logger creation in AbstractBinary

[ckrack]

I am using Alchemy/Binarydriver through PHP-FFMPeg.

When no logger is set through the configuration, the typehint in Alchemy\BinaryDriver\AbstractBinary::__construct() fails.

Catchable fatal error: Argument 2 passed to Alchemy\BinaryDriver\AbstractBinary::__construct() must be an instance of Psr\Log\LoggerInterface, instance of Monolog\Logger given, called in /vendor/alchemy/binary-driver/src/Alchemy/BinaryDriver/AbstractBinary.php on line 171 and defined in /vendor/alchemy/binary-driver/src/Alchemy/BinaryDriver/AbstractBinary.php on line 39

in AbstractBinary::load, $logger is null.
This leads to: this line being called:
$logger = new Logger(__NAMESPACE__ . ' logger');

__NAMESPACE__ is:
string 'Alchemy\BinaryDriver' (length=20)

Logger is referenced as:
use Monolog\Logger;
in Line 19.

This leads to $logger being the following at the end of the call to AbstractBinary::load:

object(Monolog\Logger)[21]
  protected 'name' => string 'Alchemy\BinaryDriver logger' (length=27)
  protected 'handlers' => 
    array (size=1)
      0 => 
        object(Monolog\Handler\NullHandler)[23]
          protected 'level' => int 100
          protected 'bubble' => boolean false
          protected 'formatter' => null
          protected 'processors' => 
            array (size=0)
              empty
  protected 'processors' => 
    array (size=0)
      empty

Monolog/Logger Version is: "dev-master": "1.13.x-dev"
This is installed through composer requirements following from php-ffmpeg.

Monolog\Logger correctly implements Loggerinterface though.
class Logger implements LoggerInterface

Is this a PHP bug?
My PHP Version is 5.6.2 on OSX.