diff --git a/activitypub.php b/activitypub.php
index b72901b..1a23d8d 100644
--- a/activitypub.php
+++ b/activitypub.php
@@ -25,6 +25,7 @@ function init() {
 	\defined( 'ACTIVITYPUB_USERNAME_REGEXP' ) || \define( 'ACTIVITYPUB_USERNAME_REGEXP', '(?:([A-Za-z0-9_-]+)@((?:[A-Za-z0-9_-]+\.)+[A-Za-z]+))' );
 	\defined( 'ACTIVITYPUB_ALLOWED_HTML' ) || \define( 'ACTIVITYPUB_ALLOWED_HTML', '<strong><a><p><ul><ol><li><code><blockquote><pre><img>' );
 	\defined( 'ACTIVITYPUB_CUSTOM_POST_CONTENT' ) || \define( 'ACTIVITYPUB_CUSTOM_POST_CONTENT', "<p><strong>[ap_title]</strong></p>\n\n[ap_content]\n\n<p>[ap_hashtags]</p>\n\n<p>[ap_shortlink]</p>" );
+	\defined( 'ACTIVITYPUB_USER_DESCRIPTION_KEY' ) || \define( 'ACTIVITYPUB_USER_DESCRIPTION_KEY', 'activitypub_user_description' );
 	\define( 'ACTIVITYPUB_PLUGIN_DIR', plugin_dir_path( __FILE__ ) );
 	\define( 'ACTIVITYPUB_PLUGIN_BASENAME', plugin_basename( __FILE__ ) );
 	\define( 'ACTIVITYPUB_PLUGIN_FILE', plugin_dir_path( __FILE__ ) . '/' . basename( __FILE__ ) );