diff --git a/src/activitypub/helpers.js b/src/activitypub/helpers.js
index 88e01123a9..71639298fb 100644
--- a/src/activitypub/helpers.js
+++ b/src/activitypub/helpers.js
@@ -353,3 +353,6 @@ Helpers.remoteAnchorToLocalProfile = async (content) => {
 
 	return content;
 };
+
+// eslint-disable-next-line max-len
+Helpers.makeSet = (object, properties) => new Set(properties.reduce((memo, property) => memo.concat(Array.isArray(object[property]) ? object[property] : [object[property]]), []));
diff --git a/src/activitypub/mocks.js b/src/activitypub/mocks.js
index b974b65417..3c657ba912 100644
--- a/src/activitypub/mocks.js
+++ b/src/activitypub/mocks.js
@@ -101,7 +101,7 @@ Mocks.post = async (objects) => {
 			attributedTo: uid,
 			inReplyTo: toPid,
 			published, updated, name, content, sourceContent,
-			to, cc, attachment, tag,
+			to, cc, audience, attachment, tag,
 			// conversation, // mastodon-specific, ignored.
 		} = object;
 
@@ -128,7 +128,7 @@ Mocks.post = async (objects) => {
 
 			edited,
 			editor: edited ? uid : undefined,
-			_activitypub: { to, cc, attachment, tag, url },
+			_activitypub: { to, cc, audience, attachment, tag, url },
 		};
 
 		return payload;