diff --git a/test/CommonMarkTest.php b/test/CommonMarkTest.php
index c7a1d52..18bca8b 100644
--- a/test/CommonMarkTest.php
+++ b/test/CommonMarkTest.php
@@ -13,8 +13,6 @@ class CommonMarkTest extends PHPUnit_Framework_TestCase
 
     protected function setUp()
     {
-        require_once(__DIR__ . '/TestParsedown.php');
-
         $this->parsedown = new TestParsedown();
         $this->parsedown->setUrlsLinked(false);
     }
diff --git a/test/ParsedownTest.php b/test/ParsedownTest.php
index c922ab1..7d07183 100644
--- a/test/ParsedownTest.php
+++ b/test/ParsedownTest.php
@@ -27,7 +27,7 @@ class ParsedownTest extends PHPUnit_Framework_TestCase
      */
     protected function initParsedown()
     {
-        $Parsedown = new Parsedown();
+        $Parsedown = new TestParsedown();
 
         return $Parsedown;
     }
@@ -132,15 +132,14 @@ color: red;
 <p>comment</p>
 <p>&lt;!-- html comment --&gt;</p>
 EXPECTED_HTML;
-        $parsedownWithNoMarkup = new Parsedown();
+
+        $parsedownWithNoMarkup = new TestParsedown();
         $parsedownWithNoMarkup->setMarkupEscaped(true);
         $this->assertEquals($expectedHtml, $parsedownWithNoMarkup->text($markdownWithHtml));
     }
 
     public function testLateStaticBinding()
     {
-        include 'test/TestParsedown.php';
-
         $parsedown = Parsedown::instance();
         $this->assertInstanceOf('Parsedown', $parsedown);
 
diff --git a/test/bootstrap.php b/test/bootstrap.php
index 5f264d2..76011c9 100644
--- a/test/bootstrap.php
+++ b/test/bootstrap.php
@@ -1,3 +1,17 @@
 <?php
 
-include 'Parsedown.php';
\ No newline at end of file
+// prepare composer autoloader
+if (is_file(__DIR__ . '/../vendor/autoload.php')) {
+    // composer root package
+    require_once(__DIR__ . '/../vendor/autoload.php');
+} elseif (is_file(__DIR__ . '/../../../../vendor/autoload.php')) {
+    // composer dependency package
+    require_once(__DIR__ . '/../../../../vendor/autoload.php');
+} else {
+    die("Cannot find `vendor/autoload.php`. Run `composer install`.");
+}
+
+// load TestParsedown class
+if (!class_exists('TestParsedown', false) && is_file('test/TestParsedown.php')) {
+    require_once('test/TestParsedown.php');
+}