diff --git a/plugins/libkolab/lib/kolab_storage_folder.php b/plugins/libkolab/lib/kolab_storage_folder.php
index 01e465fd..2e50753a 100644
--- a/plugins/libkolab/lib/kolab_storage_folder.php
+++ b/plugins/libkolab/lib/kolab_storage_folder.php
@@ -277,7 +277,7 @@ class kolab_storage_folder
                 'type' => 'php',
                 'file' => __FILE__,
                 'line' => __LINE__,
-                'message' => "Could not find Kolab data part in message " . $this->name . ':' . $uid,
+                'message' => "Could not find Kolab data part in message $msguid ($this->name).",
             ), true);
             return false;
         }
diff --git a/plugins/libkolab/libkolab.php b/plugins/libkolab/libkolab.php
index 9092f463..eefc621b 100644
--- a/plugins/libkolab/libkolab.php
+++ b/plugins/libkolab/libkolab.php
@@ -35,6 +35,9 @@ class libkolab extends rcube_plugin
         // load local config
         $this->load_config();
 
+        // require kolab_folders plugin for listing folders by type (annotation)
+        $this->require_plugin('kolab_folders');
+
         // extend include path to load bundled lib classes
         $include_path = $this->home . '/lib' . PATH_SEPARATOR . ini_get('include_path');
         set_include_path($include_path);