diff --git a/plugins/OStatus/lib/salmonaction.php b/plugins/OStatus/lib/salmonaction.php
index 3b9472eeb8..4d2144c300 100644
--- a/plugins/OStatus/lib/salmonaction.php
+++ b/plugins/OStatus/lib/salmonaction.php
@@ -31,6 +31,8 @@ class SalmonAction extends Action
     protected $oprofile = null; // Ostatus_profile of the actor
     protected $actor    = null; // Profile object of the actor
 
+    var $format   = 'text'; // error messages will be printed in plaintext
+
     var $xml      = null;
     var $activity = null;
     var $target   = null;