--- activitystream.module
+++ (clipboard)
@@ -426,6 +426,9 @@
     'activitystream' => array(
       'arguments' => array('items' => NULL),
     ),
+    'activitystream_header' => array(
+      'arguments' => array('action' => NULL),
+    ),
     'activitystream_date' => array(
       'arguments' => array('date' => NULL),
     ),