diff --git a/includes/class-setup.php b/includes/class-setup.php
index 67877fb..a02076c 100644
--- a/includes/class-setup.php
+++ b/includes/class-setup.php
@@ -272,6 +272,7 @@ class Setup {
 		foreach ( $this->active_event_plugins as $event_plugin ) {
 			if ( ! in_array( $event_plugin->get_post_type(), $activitypub_supported_post_types, true ) ) {
 				$activitypub_supported_post_types[] = $event_plugin->get_post_type();
+				add_post_type_support( $event_plugin->get_post_type(), 'activitypub' );
 			}
 		}
 		update_option( 'activitypub_support_post_types', $activitypub_supported_post_types );