diff --git a/plugins/libcalendaring/libcalendaring.php b/plugins/libcalendaring/libcalendaring.php
index a3cf48d2..0ee7af9a 100644
--- a/plugins/libcalendaring/libcalendaring.php
+++ b/plugins/libcalendaring/libcalendaring.php
@@ -835,7 +835,7 @@ class libcalendaring extends rcube_plugin
                 $more    = true;
             }
 
-            $output  = '; ' . $this->gettext('except') . ' ' . join(', ', $exdates)
+            $output  .= '; ' . $this->gettext('except') . ' ' . join(', ', $exdates)
                 . ($more ? '...' : '');
         }