diff --git a/system/classes/kohana.php b/system/classes/kohana.php
index 6684c72..c833225 100644
--- a/system/classes/kohana.php
+++ b/system/classes/kohana.php
@@ -493,7 +493,7 @@ final class Kohana {
 	 */
 	public static function list_files($directory = NULL)
 	{
-		if ( ! empty($directory))
+		if ($directory !== NULL)
 		{
 			// Add the directory separator
 			$directory .= DIRECTORY_SEPARATOR;