diff --git a/plugins/kolab_core/README.txt b/plugins/kolab_core/README.txt
index 87537c0b..751e84fb 100644
--- a/plugins/kolab_core/README.txt
+++ b/plugins/kolab_core/README.txt
@@ -24,6 +24,8 @@ pear install horde/Log
 pear install horde/Kolab_Format
 pear install horde/Kolab_Storage
 
+WARNING: This procedure installs Horde4 sources that doesn't work with this plugin!
+
 
 Configuration
 -------------
diff --git a/plugins/kolab_core/rcube_kolab.php b/plugins/kolab_core/rcube_kolab.php
index fb9c975e..3c875ba4 100644
--- a/plugins/kolab_core/rcube_kolab.php
+++ b/plugins/kolab_core/rcube_kolab.php
@@ -1,5 +1,7 @@
 <?php
 
+ini_set('error_reporting', E_ALL&~(E_DEPRECATED | E_NOTICE));
+
 require_once 'Horde/Kolab/Storage/List.php';
 require_once 'Horde/Kolab/Format.php';
 require_once 'Horde/Auth.php';