diff --git a/classes/Autoload.php b/classes/Autoload.php
index 7f20b0cf9..dc1966d8e 100644
--- a/classes/Autoload.php
+++ b/classes/Autoload.php
@@ -81,7 +81,8 @@ class Autoload
 			return;
 
 		// regenerate the class index if the requested file doesn't exists
-		if ((isset($this->index[$classname]) && $this->index[$classname] && !is_file($this->root_dir.$this->index[$classname]))
+		if (!isset($this->index[$classname])
+			|| ($this->index[$classname] && !is_file($this->root_dir.$this->index[$classname]))
 			|| (isset($this->index[$classname.'Core']) && $this->index[$classname.'Core'] && !is_file($this->root_dir.$this->index[$classname.'Core'])))
 			$this->generateIndex();