diff --git a/AmazonPay/Client.php b/AmazonPay/Client.php
index 5169a7e..20851aa 100644
--- a/AmazonPay/Client.php
+++ b/AmazonPay/Client.php
@@ -11,13 +11,7 @@
 require_once 'HttpCurl.php';
 require_once 'ClientInterface.php';
 require_once 'Regions.php';
-if (!interface_exists('\Psr\Log\LoggerAwareInterface')) {
-    require_once(__DIR__.'/../Psr/Log/LoggerAwareInterface.php');
-}
 
-if (!interface_exists('\Psr\Log\LoggerInterface')) {
-    require_once(__DIR__.'/../Psr/Log/LoggerInterface.php');
-}
 use Psr\Log\LoggerAwareInterface;
 use Psr\Log\LoggerInterface;
 
diff --git a/AmazonPay/IpnHandler.php b/AmazonPay/IpnHandler.php
index dd49823..3693181 100644
--- a/AmazonPay/IpnHandler.php
+++ b/AmazonPay/IpnHandler.php
@@ -8,12 +8,6 @@
 
 require_once 'HttpCurl.php';
 require_once 'IpnHandlerInterface.php';
-if (!interface_exists('\Psr\Log\LoggerAwareInterface')) {
-    require_once(__DIR__.'/../Psr/Log/LoggerAwareInterface.php');
-}
-if (!interface_exists('\Psr\Log\LoggerInterface')) {
-    require_once(__DIR__.'/../Psr/Log/LoggerInterface.php');
-}
 use Psr\Log\LoggerAwareInterface;
 use Psr\Log\LoggerInterface;
 
diff --git a/Psr/Log/AbstractLogger.php b/Psr/Log/AbstractLogger.php
deleted file mode 100755
index 5a68a23..0000000
--- a/Psr/Log/AbstractLogger.php
+++ /dev/null
@@ -1,128 +0,0 @@
-<?php
-
-namespace Psr\Log;
-
-/**
- * This is a simple Logger implementation that other Loggers can inherit from.
- *
- * It simply delegates all log-level-specific methods to the `log` method to
- * reduce boilerplate code that a simple Logger that does the same thing with
- * messages regardless of the error level has to implement.
- */
-abstract class AbstractLogger implements LoggerInterface
-{
-    /**
-     * System is unusable.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function emergency($message, array $context = array())
-    {
-        $this->log(LogLevel::EMERGENCY, $message, $context);
-    }
-
-    /**
-     * Action must be taken immediately.
-     *
-     * Example: Entire website down, database unavailable, etc. This should
-     * trigger the SMS alerts and wake you up.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function alert($message, array $context = array())
-    {
-        $this->log(LogLevel::ALERT, $message, $context);
-    }
-
-    /**
-     * Critical conditions.
-     *
-     * Example: Application component unavailable, unexpected exception.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function critical($message, array $context = array())
-    {
-        $this->log(LogLevel::CRITICAL, $message, $context);
-    }
-
-    /**
-     * Runtime errors that do not require immediate action but should typically
-     * be logged and monitored.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function error($message, array $context = array())
-    {
-        $this->log(LogLevel::ERROR, $message, $context);
-    }
-
-    /**
-     * Exceptional occurrences that are not errors.
-     *
-     * Example: Use of deprecated APIs, poor use of an API, undesirable things
-     * that are not necessarily wrong.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function warning($message, array $context = array())
-    {
-        $this->log(LogLevel::WARNING, $message, $context);
-    }
-
-    /**
-     * Normal but significant events.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function notice($message, array $context = array())
-    {
-        $this->log(LogLevel::NOTICE, $message, $context);
-    }
-
-    /**
-     * Interesting events.
-     *
-     * Example: User logs in, SQL logs.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function info($message, array $context = array())
-    {
-        $this->log(LogLevel::INFO, $message, $context);
-    }
-
-    /**
-     * Detailed debug information.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function debug($message, array $context = array())
-    {
-        $this->log(LogLevel::DEBUG, $message, $context);
-    }
-}
diff --git a/Psr/Log/InvalidArgumentException.php b/Psr/Log/InvalidArgumentException.php
deleted file mode 100755
index 67f852d..0000000
--- a/Psr/Log/InvalidArgumentException.php
+++ /dev/null
@@ -1,7 +0,0 @@
-<?php
-
-namespace Psr\Log;
-
-class InvalidArgumentException extends \InvalidArgumentException
-{
-}
diff --git a/Psr/Log/LogLevel.php b/Psr/Log/LogLevel.php
deleted file mode 100755
index 9cebcac..0000000
--- a/Psr/Log/LogLevel.php
+++ /dev/null
@@ -1,18 +0,0 @@
-<?php
-
-namespace Psr\Log;
-
-/**
- * Describes log levels.
- */
-class LogLevel
-{
-    const EMERGENCY = 'emergency';
-    const ALERT     = 'alert';
-    const CRITICAL  = 'critical';
-    const ERROR     = 'error';
-    const WARNING   = 'warning';
-    const NOTICE    = 'notice';
-    const INFO      = 'info';
-    const DEBUG     = 'debug';
-}
diff --git a/Psr/Log/LoggerAwareInterface.php b/Psr/Log/LoggerAwareInterface.php
deleted file mode 100755
index e84191b..0000000
--- a/Psr/Log/LoggerAwareInterface.php
+++ /dev/null
@@ -1,18 +0,0 @@
-<?php
-
-namespace Psr\Log;
-
-/**
- * Describes a logger-aware instance.
- */
-interface LoggerAwareInterface
-{
-    /**
-     * Sets a logger instance on the object.
-     *
-     * @param LoggerInterface $logger
-     *
-     * @return null
-     */
-    public function setLogger(LoggerInterface $logger);
-}
diff --git a/Psr/Log/LoggerAwareTrait.php b/Psr/Log/LoggerAwareTrait.php
deleted file mode 100755
index 639f79b..0000000
--- a/Psr/Log/LoggerAwareTrait.php
+++ /dev/null
@@ -1,26 +0,0 @@
-<?php
-
-namespace Psr\Log;
-
-/**
- * Basic Implementation of LoggerAwareInterface.
- */
-trait LoggerAwareTrait
-{
-    /**
-     * The logger instance.
-     *
-     * @var LoggerInterface
-     */
-    protected $logger;
-
-    /**
-     * Sets a logger.
-     *
-     * @param LoggerInterface $logger
-     */
-    public function setLogger(LoggerInterface $logger)
-    {
-        $this->logger = $logger;
-    }
-}
diff --git a/Psr/Log/LoggerInterface.php b/Psr/Log/LoggerInterface.php
deleted file mode 100755
index 16c04ad..0000000
--- a/Psr/Log/LoggerInterface.php
+++ /dev/null
@@ -1,123 +0,0 @@
-<?php
-
-namespace Psr\Log;
-
-/**
- * Describes a logger instance.
- *
- * The message MUST be a string or object implementing __toString().
- *
- * The message MAY contain placeholders in the form: {foo} where foo
- * will be replaced by the context data in key "foo".
- *
- * The context array can contain arbitrary data. The only assumption that
- * can be made by implementors is that if an Exception instance is given
- * to produce a stack trace, it MUST be in a key named "exception".
- *
- * See https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-3-logger-interface.md
- * for the full interface specification.
- */
-interface LoggerInterface
-{
-    /**
-     * System is unusable.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function emergency($message, array $context = array());
-
-    /**
-     * Action must be taken immediately.
-     *
-     * Example: Entire website down, database unavailable, etc. This should
-     * trigger the SMS alerts and wake you up.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function alert($message, array $context = array());
-
-    /**
-     * Critical conditions.
-     *
-     * Example: Application component unavailable, unexpected exception.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function critical($message, array $context = array());
-
-    /**
-     * Runtime errors that do not require immediate action but should typically
-     * be logged and monitored.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function error($message, array $context = array());
-
-    /**
-     * Exceptional occurrences that are not errors.
-     *
-     * Example: Use of deprecated APIs, poor use of an API, undesirable things
-     * that are not necessarily wrong.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function warning($message, array $context = array());
-
-    /**
-     * Normal but significant events.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function notice($message, array $context = array());
-
-    /**
-     * Interesting events.
-     *
-     * Example: User logs in, SQL logs.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function info($message, array $context = array());
-
-    /**
-     * Detailed debug information.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function debug($message, array $context = array());
-
-    /**
-     * Logs with an arbitrary level.
-     *
-     * @param mixed  $level
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function log($level, $message, array $context = array());
-}
diff --git a/Psr/Log/LoggerTrait.php b/Psr/Log/LoggerTrait.php
deleted file mode 100755
index d8c611b..0000000
--- a/Psr/Log/LoggerTrait.php
+++ /dev/null
@@ -1,140 +0,0 @@
-<?php
-
-namespace Psr\Log;
-
-/**
- * This is a simple Logger trait that classes unable to extend AbstractLogger
- * (because they extend another class, etc) can include.
- *
- * It simply delegates all log-level-specific methods to the `log` method to
- * reduce boilerplate code that a simple Logger that does the same thing with
- * messages regardless of the error level has to implement.
- */
-trait LoggerTrait
-{
-    /**
-     * System is unusable.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function emergency($message, array $context = array())
-    {
-        $this->log(LogLevel::EMERGENCY, $message, $context);
-    }
-
-    /**
-     * Action must be taken immediately.
-     *
-     * Example: Entire website down, database unavailable, etc. This should
-     * trigger the SMS alerts and wake you up.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function alert($message, array $context = array())
-    {
-        $this->log(LogLevel::ALERT, $message, $context);
-    }
-
-    /**
-     * Critical conditions.
-     *
-     * Example: Application component unavailable, unexpected exception.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function critical($message, array $context = array())
-    {
-        $this->log(LogLevel::CRITICAL, $message, $context);
-    }
-
-    /**
-     * Runtime errors that do not require immediate action but should typically
-     * be logged and monitored.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function error($message, array $context = array())
-    {
-        $this->log(LogLevel::ERROR, $message, $context);
-    }
-
-    /**
-     * Exceptional occurrences that are not errors.
-     *
-     * Example: Use of deprecated APIs, poor use of an API, undesirable things
-     * that are not necessarily wrong.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function warning($message, array $context = array())
-    {
-        $this->log(LogLevel::WARNING, $message, $context);
-    }
-
-    /**
-     * Normal but significant events.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function notice($message, array $context = array())
-    {
-        $this->log(LogLevel::NOTICE, $message, $context);
-    }
-
-    /**
-     * Interesting events.
-     *
-     * Example: User logs in, SQL logs.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function info($message, array $context = array())
-    {
-        $this->log(LogLevel::INFO, $message, $context);
-    }
-
-    /**
-     * Detailed debug information.
-     *
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function debug($message, array $context = array())
-    {
-        $this->log(LogLevel::DEBUG, $message, $context);
-    }
-
-    /**
-     * Logs with an arbitrary level.
-     *
-     * @param mixed  $level
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    abstract public function log($level, $message, array $context = array());
-}
diff --git a/Psr/Log/NullLogger.php b/Psr/Log/NullLogger.php
deleted file mode 100755
index 3fc5100..0000000
--- a/Psr/Log/NullLogger.php
+++ /dev/null
@@ -1,28 +0,0 @@
-<?php
-
-namespace Psr\Log;
-
-/**
- * This Logger can be used to avoid conditional log calls.
- *
- * Logging should always be optional, and if no logger is provided to your
- * library creating a NullLogger instance to have something to throw logs at
- * is a good way to avoid littering your code with `if ($this->logger) { }`
- * blocks.
- */
-class NullLogger extends AbstractLogger
-{
-    /**
-     * Logs with an arbitrary level.
-     *
-     * @param mixed  $level
-     * @param string $message
-     * @param array  $context
-     *
-     * @return null
-     */
-    public function log($level, $message, array $context = array())
-    {
-        // noop
-    }
-}
diff --git a/Psr/Log/Test/LoggerInterfaceTest.php b/Psr/Log/Test/LoggerInterfaceTest.php
deleted file mode 100755
index 06f250d..0000000
--- a/Psr/Log/Test/LoggerInterfaceTest.php
+++ /dev/null
@@ -1,133 +0,0 @@
-<?php
-
-namespace Psr\Log\Test;
-
-use Psr\Log\LoggerInterface;
-use Psr\Log\LogLevel;
-
-/**
- * Provides a base test class for ensuring compliance with the LoggerInterface.
- *
- * Implementors can extend the class and implement abstract methods to run this
- * as part of their test suite.
- */
-abstract class LoggerInterfaceTest extends \PHPUnit_Framework_TestCase
-{
-    /**
-     * @return LoggerInterface
-     */
-    abstract public function getLogger();
-
-    /**
-     * This must return the log messages in order.
-     *
-     * The simple formatting of the messages is: "<LOG LEVEL> <MESSAGE>".
-     *
-     * Example ->error('Foo') would yield "error Foo".
-     *
-     * @return string[]
-     */
-    abstract public function getLogs();
-
-    public function testImplements()
-    {
-        $this->assertInstanceOf('Psr\Log\LoggerInterface', $this->getLogger());
-    }
-
-    /**
-     * @dataProvider provideLevelsAndMessages
-     */
-    public function testLogsAtAllLevels($level, $message)
-    {
-        $logger = $this->getLogger();
-        $logger->{$level}($message, array('user' => 'Bob'));
-        $logger->log($level, $message, array('user' => 'Bob'));
-
-        $expected = array(
-            $level.' message of level '.$level.' with context: Bob',
-            $level.' message of level '.$level.' with context: Bob',
-        );
-        $this->assertEquals($expected, $this->getLogs());
-    }
-
-    public function provideLevelsAndMessages()
-    {
-        return array(
-            LogLevel::EMERGENCY => array(LogLevel::EMERGENCY, 'message of level emergency with context: {user}'),
-            LogLevel::ALERT => array(LogLevel::ALERT, 'message of level alert with context: {user}'),
-            LogLevel::CRITICAL => array(LogLevel::CRITICAL, 'message of level critical with context: {user}'),
-            LogLevel::ERROR => array(LogLevel::ERROR, 'message of level error with context: {user}'),
-            LogLevel::WARNING => array(LogLevel::WARNING, 'message of level warning with context: {user}'),
-            LogLevel::NOTICE => array(LogLevel::NOTICE, 'message of level notice with context: {user}'),
-            LogLevel::INFO => array(LogLevel::INFO, 'message of level info with context: {user}'),
-            LogLevel::DEBUG => array(LogLevel::DEBUG, 'message of level debug with context: {user}'),
-        );
-    }
-
-    /**
-     * @expectedException \Psr\Log\InvalidArgumentException
-     */
-    public function testThrowsOnInvalidLevel()
-    {
-        $logger = $this->getLogger();
-        $logger->log('invalid level', 'Foo');
-    }
-
-    public function testContextReplacement()
-    {
-        $logger = $this->getLogger();
-        $logger->info('{Message {nothing} {user} {foo.bar} a}', array('user' => 'Bob', 'foo.bar' => 'Bar'));
-
-        $expected = array('info {Message {nothing} Bob Bar a}');
-        $this->assertEquals($expected, $this->getLogs());
-    }
-
-    public function testObjectCastToString()
-    {
-        $dummy = $this->getMock('Psr\Log\Test\DummyTest', array('__toString'));
-        $dummy->expects($this->once())
-            ->method('__toString')
-            ->will($this->returnValue('DUMMY'));
-
-        $this->getLogger()->warning($dummy);
-
-        $expected = array('warning DUMMY');
-        $this->assertEquals($expected, $this->getLogs());
-    }
-
-    public function testContextCanContainAnything()
-    {
-        $context = array(
-            'bool' => true,
-            'null' => null,
-            'string' => 'Foo',
-            'int' => 0,
-            'float' => 0.5,
-            'nested' => array('with object' => new DummyTest),
-            'object' => new \DateTime,
-            'resource' => fopen('php://memory', 'r'),
-        );
-
-        $this->getLogger()->warning('Crazy context data', $context);
-
-        $expected = array('warning Crazy context data');
-        $this->assertEquals($expected, $this->getLogs());
-    }
-
-    public function testContextExceptionKeyCanBeExceptionOrOtherValues()
-    {
-        $logger = $this->getLogger();
-        $logger->warning('Random message', array('exception' => 'oops'));
-        $logger->critical('Uncaught Exception!', array('exception' => new \LogicException('Fail')));
-
-        $expected = array(
-            'warning Random message',
-            'critical Uncaught Exception!'
-        );
-        $this->assertEquals($expected, $this->getLogs());
-    }
-}
-
-class DummyTest
-{
-}
diff --git a/composer.json b/composer.json
index 2c4e487..c8d00ed 100644
--- a/composer.json
+++ b/composer.json
@@ -27,6 +27,15 @@
    },
    "require": {
       "ext-curl": "*",
-      "php": ">=5.5.0"
+      "php": ">=5.5.0",
+      "psr/log": "^1.0"
+   },
+   "require-dev": {
+      "phpunit/phpunit": "^4"
+   },
+   "scripts": {
+      "test": [
+         "phpunit"
+      ]
    }
 }
diff --git a/phpunit.xml b/phpunit.xml
new file mode 100644
index 0000000..d982dcc
--- /dev/null
+++ b/phpunit.xml
@@ -0,0 +1,11 @@
+<phpunit
+        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:noNamespaceSchemaLocation="http://schema.phpunit.de/4.8/phpunit.xsd"
+        bootstrap="tst/bootstrap-phpunit.php">
+
+    <testsuites>
+        <testsuite name="Core tests">
+            <directory>tst/unit</directory>
+        </testsuite>
+    </testsuites>
+</phpunit>
diff --git a/tst/bootstrap-phpunit.php b/tst/bootstrap-phpunit.php
new file mode 100644
index 0000000..c33c493
--- /dev/null
+++ b/tst/bootstrap-phpunit.php
@@ -0,0 +1,2 @@
+<?php
+require_once __DIR__ . '/../../vendor/autoload.php';