diff --git a/application/helpers/config_helper.php b/application/helpers/config_helper.php
index a404ce83..1ee828f0 100644
--- a/application/helpers/config_helper.php
+++ b/application/helpers/config_helper.php
@@ -34,7 +34,7 @@ function config($key, $default = NULL)
     /** @var EA_Controller $CI */
     $CI = &get_instance();
 
-    if (is_null($key))
+    if (empty($key))
     {
         throw new InvalidArgumentException('The $key argument cannot be empty.');
     }