diff --git a/plugins/libkolab/lib/kolab_storage.php b/plugins/libkolab/lib/kolab_storage.php
--- a/plugins/libkolab/lib/kolab_storage.php
+++ b/plugins/libkolab/lib/kolab_storage.php
@@ -1093,6 +1093,14 @@
         return $_folders;
     }
 
+    /**
+     * Clears the internal typedata cache
+     */
+    public static function clear_typedata_cache()
+    {
+        self::$typedata = null;
+    }
+
     /**
      * Returns folder types indexed by folder name
      *