diff --git a/composer.json b/composer.json
index f7e6c2e..478bb6b 100644
--- a/composer.json
+++ b/composer.json
@@ -34,6 +34,7 @@
 	},
 	"require-dev": {
 		"leafo/lessphp": "~0.4.0",
+		"leafo/scssphp": "^0.3.0",
 		"meenie/javascript-packer": "~1.1",
 		"phpunit/phpunit": "4.8.*",
 		"tedivm/jshrink": "~1.1.0"
diff --git a/lib/Minify/ScssCssSource.php b/lib/Minify/ScssCssSource.php
new file mode 100644
index 0000000..038a03f
--- /dev/null
+++ b/lib/Minify/ScssCssSource.php
@@ -0,0 +1,175 @@
+<?php
+use Leafo\ScssPhp\Compiler;
+use Leafo\ScssPhp\Server;
+use Leafo\ScssPhp\Version;
+
+/**
+ * Class for using SCSS files
+ *
+ * @link https://github.com/leafo/scssphp/
+ */
+class Minify_ScssCssSource extends Minify_Source {
+    /**
+     * @var Minify_CacheInterface
+     */
+    private $cache;
+
+    /**
+     * Parsed SCSS cache object
+     *
+     * @var array
+     */
+    private $parsed;
+
+    /**
+     * @inheritdoc
+     */
+    public function __construct(array $spec, Minify_CacheInterface $cache)
+    {
+        parent::__construct($spec);
+
+        $this->cache = $cache;
+    }
+
+    /**
+     * Get last modified of all parsed files
+     *
+     * @return int
+     */
+    public function getLastModified()
+    {
+        $cache = $this->getCache();
+
+        return $cache['updated'];
+    }
+
+    /**
+     * Get content
+     *
+     * @return string
+     */
+    public function getContent()
+    {
+        $cache = $this->getCache();
+
+        return $cache['content'];
+    }
+
+    /**
+     * Make a unique cache id for for this source.
+     *
+     * @param string $prefix
+     *
+     * @return string
+     */
+    private function getCacheId($prefix = 'minify')
+    {
+        $md5 = md5($this->filepath);
+
+        return "{$prefix}_scss_{$md5}";
+    }
+
+    /**
+     * Get SCSS cache object
+     *
+     * Runs the compilation if needed
+     *
+     * Implements Leafo\ScssPhp\Server logic because we need to get parsed files without parsing actual content
+     *
+     * @return array
+     */
+    private function getCache()
+    {
+        // cache for single run
+        // so that getLastModified and getContent in single request do not add additional cache roundtrips (i.e memcache)
+        if (isset($this->parsed)) {
+            return $this->parsed;
+        }
+
+        // check from cache first
+        $cache = null;
+        $cacheId = $this->getCacheId();
+        if ($this->cache->isValid($cacheId, 0)) {
+            if ($cache = $this->cache->fetch($cacheId)) {
+                $cache = unserialize($cache);
+            }
+        }
+
+        $input = $cache ? $cache : $this->filepath;
+
+        if ($this->cacheIsStale($cache)) {
+            $cache = $this->compile($this->filepath);
+        }
+
+        if (!is_array($input) || $cache['updated'] > $input['updated']) {
+            $this->cache->store($cacheId, serialize($cache));
+        }
+
+        return $this->parsed = $cache;
+    }
+
+    /**
+     * Determine whether .scss file needs to be re-compiled.
+     *
+     * @param array $cache Cache object
+     *
+     * @return boolean True if compile required.
+     */
+    private function cacheIsStale($cache)
+    {
+        if (!$cache) {
+            return true;
+        }
+
+        $updated = $cache['updated'];
+        foreach ($cache['files'] as $import => $mtime) {
+            $filemtime = filemtime($import);
+
+            if ($filemtime !== $mtime || $filemtime > $updated) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * Compile .scss file
+     *
+     * @param string $filename Input path (.scss)
+     *
+     * @see Server::compile()
+     * @return array meta data result of the compile
+     */
+    private function compile($filename)
+    {
+        $start = microtime(true);
+        $scss = new Compiler();
+
+	    // set import path directory the input filename resides
+	    // otherwise @import statements will not find the files
+        // and will treat the @import line as css import
+	    $scss->setImportPaths(dirname($filename));
+
+	    $css = $scss->compile(file_get_contents($filename), $filename);
+        $elapsed = round((microtime(true) - $start), 4);
+
+        $v = Version::VERSION;
+        $ts = date('r', $start);
+        $css = "/* compiled by scssphp $v on $ts (${elapsed}s) */\n\n" . $css;
+
+        $imports = $scss->getParsedFiles();
+
+        $updated = 0;
+        foreach ($imports as $mtime) {
+            $updated = max($updated, $mtime);
+        }
+
+        return array(
+            'elapsed' => $elapsed, // statistic, can be dropped
+            'updated' => $updated,
+            'content' => $css,
+            'files' => $imports,
+        );
+    }
+}
diff --git a/lib/Minify/Source/Factory.php b/lib/Minify/Source/Factory.php
index 7033179..71d7f08 100644
--- a/lib/Minify/Source/Factory.php
+++ b/lib/Minify/Source/Factory.php
@@ -67,9 +67,13 @@ class Minify_Source_Factory {
             throw new InvalidArgumentException("fileChecker option is not callable");
         }
 
-	    $this->setHandler('~\.less$~i', function ($spec) use ($cache) {
-		    return new Minify_LessCssSource($spec, $cache);
-	    });
+        $this->setHandler('~\.less$~i', function ($spec) use ($cache) {
+            return new Minify_LessCssSource($spec, $cache);
+        });
+
+        $this->setHandler('~\.scss~i', function ($spec) use ($cache) {
+            return new Minify_ScssCssSource($spec, $cache);
+        });
 
         $this->setHandler('~\.(js|css)$~i', function ($spec) {
             return new Minify_Source($spec);
diff --git a/tests/ScssSourceTest.php b/tests/ScssSourceTest.php
new file mode 100644
index 0000000..a1581ef
--- /dev/null
+++ b/tests/ScssSourceTest.php
@@ -0,0 +1,40 @@
+<?php
+
+class ScssSourceTest extends TestCase
+{
+    public function setUp()
+    {
+        $this->realDocRoot = $_SERVER['DOCUMENT_ROOT'];
+        $_SERVER['DOCUMENT_ROOT'] = self::$document_root;
+    }
+
+    /**
+     * @link https://github.com/mrclay/minify/issues/500
+     */
+    public function testTimestamp()
+    {
+        $baseDir = self::$test_files;
+
+        $mainLess = "$baseDir/main.scss";
+        $includedLess = "$baseDir/_included.scss";
+
+        // touch timestamp with 1s difference
+        touch($mainLess);
+        sleep(1);
+        touch($includedLess);
+
+        $mtime1 = filemtime($mainLess);
+        var_dump($mtime1);
+        $mtime2 = filemtime($includedLess);
+        var_dump($mtime2);
+
+        $max = max($mtime1, $mtime2);
+
+        $options = array(
+            'groupsConfigFile' => "$baseDir/htmlHelper_groupsConfig.php",
+        );
+        $res = Minify_HTML_Helper::getUri('scss', $options);
+
+        $this->assertEquals("/min/g=scss&amp;{$max}", $res);
+    }
+}
\ No newline at end of file
diff --git a/tests/_test_files/_included.scss b/tests/_test_files/_included.scss
new file mode 100644
index 0000000..df8d371
--- /dev/null
+++ b/tests/_test_files/_included.scss
@@ -0,0 +1,8 @@
+/* lesstest2.scss */
+
+
+a.included {
+  color: $primary-color;
+  font-size: 13px;
+  text-decoration: none;
+}
diff --git a/tests/_test_files/htmlHelper_groupsConfig.php b/tests/_test_files/htmlHelper_groupsConfig.php
index cf67275..cbf8a9d 100644
--- a/tests/_test_files/htmlHelper_groupsConfig.php
+++ b/tests/_test_files/htmlHelper_groupsConfig.php
@@ -9,4 +9,8 @@ return array(
     'less' => array(
         '//_test_files/main.less',
     ),
+
+    'scss' => array(
+        '//_test_files/main.scss',
+    ),
 );
diff --git a/tests/_test_files/main.scss b/tests/_test_files/main.scss
new file mode 100644
index 0000000..80bc0ea
--- /dev/null
+++ b/tests/_test_files/main.scss
@@ -0,0 +1,29 @@
+/*! preserving comment */
+
+// Variable
+$primary-color: hotpink;
+
+// Mixin
+@mixin border-radius($radius) {
+  -webkit-border-radius: $radius;
+  -moz-border-radius: $radius;
+  border-radius: $radius;
+}
+
+.my-element {
+  color: $primary-color;
+  width: 100%;
+  overflow: hidden;
+}
+
+.my-other-element {
+  @include border-radius(6px);
+}
+
+/* import include -> */
+@import "_included";
+/* <- import included */
+
+/*
+ a normal comment.
+*/
\ No newline at end of file