diff --git a/application/Thumbnailer.php b/application/Thumbnailer.php
index a23f98e..d5f5ac2 100644
--- a/application/Thumbnailer.php
+++ b/application/Thumbnailer.php
@@ -55,7 +55,7 @@ class Thumbnailer
         $this->conf = $conf;
 
         if (! $this->checkRequirements()) {
-            $this->conf->set('thumbnails.enabled', false);
+            $this->conf->set('thumbnails.mode', Thumbnailer::MODE_NONE);
             $this->conf->write(true);
             // TODO: create a proper error handling system able to catch exceptions...
             die(t(