diff --git a/integration/class-friends-feed-parser-activitypub.php b/integration/class-friends-feed-parser-activitypub.php
index e360c08..a59546b 100644
--- a/integration/class-friends-feed-parser-activitypub.php
+++ b/integration/class-friends-feed-parser-activitypub.php
@@ -413,7 +413,11 @@ class Friends_Feed_Parser_ActivityPub extends \Friends\Feed_Parser {
 
 	public function get_possible_mentions() {
 		static $users = null;
-		if ( is_null( $users ) || true ) {
+		if ( ! method_exists( '\Friends\User_Feed', 'get_by_parser' ) ) {
+			return array();
+		}
+
+		if ( is_null( $users ) || ! apply_filters( 'activitypub_cache_possible_friend_mentions', true ) ) {
 			$feeds = \Friends\User_Feed::get_by_parser( 'activitypub' );
 			$users = array();
 			foreach ( $feeds as $feed ) {
diff --git a/tests/test-class-friends-feed-parser-activitypub.php b/tests/test-class-friends-feed-parser-activitypub.php
index 889d43b..55a4230 100644
--- a/tests/test-class-friends-feed-parser-activitypub.php
+++ b/tests/test-class-friends-feed-parser-activitypub.php
@@ -163,6 +163,7 @@ class Test_Friends_Feed_Parser_ActivityPub extends ActivityPub_TestCase_Cache_HT
 	}
 
 	public function test_friend_mentions() {
+		add_filter( 'friends_cache_possible_mentions', '__return_false' );
 		$post = \wp_insert_post(
 			array(
 				'post_author' => 1,
@@ -188,6 +189,8 @@ class Test_Friends_Feed_Parser_ActivityPub extends ActivityPub_TestCase_Cache_HT
 		$this->assertContains( $this->actor, $activitypub_activity->get_cc() );
 
 		remove_all_filters( 'activitypub_from_post_object' );
+		remove_all_filters( 'activitypub_cache_possible_friend_mentions' );
+
 		\wp_trash_post( $post );
 
 	}