diff --git a/test/test_webmention.py b/test/test_webmention.py
index 9dd567c7..d8ba1bd5 100644
--- a/test/test_webmention.py
+++ b/test/test_webmention.py
@@ -99,6 +99,7 @@ class WebmentionTest(testutil.TestCase):
             '@type': 'Create',
             'type': 'Create',
             'object': {
+                '@context': 'https://www.w3.org/ns/activitystreams',
                 '@type': 'Note',
                 'type': 'Note',
                 'url': 'http://a/reply',
diff --git a/webmention.py b/webmention.py
index e61da139..f9a76777 100644
--- a/webmention.py
+++ b/webmention.py
@@ -31,8 +31,8 @@ import models
 def prepare_as2(activity):
     """Prepare an AS2 object to be sent via ActivityPub."""
     activity.update({
-        'type': activity['@type'],  # for Mastodon
-        'id': activity['@id'],      # "
+        'type': activity.get('@type'),  # for Mastodon
+        'id': activity.get('@id'),      # "
         'cc': (activity.get('cc', []) +
                [activitypub.PUBLIC_AUDIENCE] +
                util.get_list(activity, 'inReplyTo')),
@@ -50,16 +50,16 @@ def prepare_as2(activity):
                             'Only using the first: %s' % in_reply_tos[0])
         activity['inReplyTo'] = in_reply_tos[0]
 
-    if activity.get('@type') in as2.TYPE_TO_VERB:
-        return activity
-    else:
-        return {
+    if activity.get('@type') not in as2.TYPE_TO_VERB:
+        activity = {
             '@context': as2.CONTEXT,
             '@type': 'Create',
             'type': 'Create',
             'object': activity,
         }
 
+    return util.trim_nulls(activity)
+
 
 class WebmentionHandler(webapp2.RequestHandler):
     """Handles inbound webmention, converts to ActivityPub or Salmon."""