diff --git a/system/src/Grav/Common/Filesystem/Folder.php b/system/src/Grav/Common/Filesystem/Folder.php
index 3d30d12eb..c839d02aa 100644
--- a/system/src/Grav/Common/Filesystem/Folder.php
+++ b/system/src/Grav/Common/Filesystem/Folder.php
@@ -44,15 +44,12 @@ abstract class Folder
     {
         $last_modified = 0;
 
-        $dirItr    = new \RecursiveDirectoryIterator($path, \RecursiveDirectoryIterator::SKIP_DOTS);
-        $filterItr = new RecursiveFileFilterIterator($dirItr);
-        $itr       = new \RecursiveIteratorIterator($filterItr, \RecursiveIteratorIterator::SELF_FIRST);
+        $dirItr = new \RecursiveDirectoryIterator($path, \RecursiveDirectoryIterator::SKIP_DOTS);
+        $itrItr = new \RecursiveIteratorIterator($dirItr, \RecursiveIteratorIterator::SELF_FIRST);
+        $itr    = new RecursiveFileFilterIterator($itrItr);
 
         /** @var \RecursiveDirectoryIterator $file */
         foreach ($itr as $file) {
-            if ($file->isDir()) {
-                continue;
-            }
             $file_modified = $file->getMTime();
             if ($file_modified > $last_modified) {
                 $last_modified = $file_modified;
diff --git a/system/src/Grav/Common/Filesystem/RecursiveFileFilterIterator.php b/system/src/Grav/Common/Filesystem/RecursiveFileFilterIterator.php
index be9667c3b..dcf1c640d 100644
--- a/system/src/Grav/Common/Filesystem/RecursiveFileFilterIterator.php
+++ b/system/src/Grav/Common/Filesystem/RecursiveFileFilterIterator.php
@@ -1,13 +1,16 @@
 <?php
 namespace Grav\Common\Filesystem;
 
-class RecursiveFileFilterIterator extends \RecursiveFilterIterator
-{
-    public static $FILTERS = ['.DS_Store'];
+use Grav\Common\Utils;
 
+class RecursiveFileFilterIterator extends \FilterIterator
+{
     public function accept()
     {
-        // Ensure any filtered file names are skipped
-        return !in_array($this->current()->getFilename(), self::$FILTERS, true);
+        // Ensure only valid file names are skipped
+        $current = $this->current()->getFilename();
+        $accept = Utils::endsWith($current, '.md');
+
+        return $accept;
     }
 }