diff --git a/tests/util/AutoloadBuilderTest.php b/tests/util/AutoloadBuilderTest.php
index f9feb7c..c31000a 100644
--- a/tests/util/AutoloadBuilderTest.php
+++ b/tests/util/AutoloadBuilderTest.php
@@ -75,7 +75,7 @@ class AutoloadBuilderTest extends PHPUnit_Framework_TestCase
     public function testBuild()
     {
         $this->setConstants();
-        $builder = new AutoloadBuilder(self::$file, array(self::$path . '/' . self::$app . '/src', self::$path . '/' . self::$app . '/cache', self::$path . '/lib'));
+        $builder = new AutoloadBuilder(self::$file, array_keys(self::$inc_dirs));
 
         $this->assertFileNotExists(self::$file);
         $builder->build();
@@ -92,18 +92,38 @@ class AutoloadBuilderTest extends PHPUnit_Framework_TestCase
     /**
      * @runInSeparateProcess
      */
+    public function testBuildWithExcluded()
+    {
+        $this->setConstants();
+        $builder = new AutoloadBuilder(self::$file, array_keys(self::$inc_dirs), array(self::$path . '/lib/core/app/'));
+
+        $this->assertFileNotExists(self::$file);
+        $builder->build();
+
+        $this->assertFileExists(self::$file);
+
+        $array = require self::$file;
+        $this->assertInternalType('array', $array);
+        $this->assertNotEmpty($array);
+        $this->assertArrayHasKey('AutoloadBuilder', $array);
+        $this->assertArrayNotHasKey('FrontController', $array);
+        $this->assertArrayNotHasKey('AjaxAction', $array);
+    }
+
+    /**
+     * @runInSeparateProcess
+     */
     public function testAccessDenied()
     {
         $this->setConstants();
 
-        $this->setExpectedException('PHPUnit_Framework_Error');
         $this->assertFileNotExists(self::$file);
 
-        touch(self::$file);
-        $this->assertFileExists(self::$file);
-        chmod(self::$file, 0400);
+        $path = dirname(self::$file);
+        chmod($path, 0400);
         $builder = new AutoloadBuilder(self::$file, array(self::$path . '/' . self::$app . '/src', self::$path . '/' . self::$app . '/cache', self::$path . '/lib'));
 
+        $this->setExpectedException('PHPUnit_Framework_Error', 'Permission denied');
         $builder->build();
         chmod(self::$file, 0777);
     }
diff --git a/util/AutoloadBuilder.php b/util/AutoloadBuilder.php
index 5c969cd..1d1dad7 100644
--- a/util/AutoloadBuilder.php
+++ b/util/AutoloadBuilder.php
@@ -46,7 +46,7 @@ class AutoloadBuilder
 
             foreach ($iterator as $file) {
 
-                if($this->isExcluded($file->getRealPath())) {
+                if ($this->isExcluded($file->getRealPath())) {
                     continue;
                 }
                 // skip non php files
@@ -70,30 +70,37 @@ class AutoloadBuilder
                     }
                 }
             }
+            unset($file);   // without this line trigger_error throws 'Serialization of 'SplFileInfo' is not allowed' exception under PHPUnit
         }
         $array_string .= ');';
         $this->writeAutoload($array_string);
-        $this->isFileConsistent();
-    }
-
-    protected function writeAutoload($string)
-    {
-        file_put_contents($this->autoload, $string);
-    }
-
-    protected function isFileConsistent()
-    {
-        $autoload_array = include($this->autoload);
-        if(!is_array($autoload_array)) {
+        if (!$this->isFileConsistent()) {
             unlink($this->autoload);
             trigger_error("Error while generating autoload file.", E_USER_ERROR);
         }
     }
 
+    protected function writeAutoload($string)
+    {
+        $pid = getmypid();
+        $tmp = dirname($this->autoload) . '/' . md5(time() + $pid);
+        file_put_contents($tmp, $string);
+        rename($tmp, $this->autoload);
+    }
+
+    protected function isFileConsistent()
+    {
+        $autoload_array = include($this->autoload);
+        if (!is_array($autoload_array)) {
+            return false;
+        }
+        return true;
+    }
+
     protected function isExcluded($file)
     {
         foreach ($this->exclude as $dir) {
-            if (stripos($file, PATH . $dir) === 0) {
+            if (stripos($file, $dir) === 0) {
                 return true;
             }
         }