diff --git a/core/AssetManager.php b/core/AssetManager.php
index 21a5662479ace4ba2915b956c3c1fc1bfadf040c..518d3110a1760fe81b215e67de5fdd00e738c39e 100644
--- a/core/AssetManager.php
+++ b/core/AssetManager.php
@@ -91,6 +91,9 @@ class Piwik_AssetManager
         }
         $rootDirectoryLen = strlen($rootDirectory);
 
+        if(!class_exists("lessc")) {
+            throw new Exception("Less was added to composer during 2.0. ==> Excecute this command to update composer packages: \$ php composer.phar update");
+        }
         $less = new lessc;
 
         // Loop through each css file