Index: src/includes/common/functions.php
===================================================================
--- src/includes/common/functions.php	(revision 5402)
+++ src/includes/common/functions.php	(working copy)
@@ -1148,7 +1148,7 @@
  *
  * @since bbPress (r5156)
  *
- * @param int $topic_id ID of the newly made reply
+ * @param int $topic_id ID of the newly made topic
  * @uses bbp_is_subscriptions_active() To check if the subscriptions are active
  * @uses bbp_get_topic_id() To validate the topic ID
  * @uses bbp_get_forum_id() To validate the forum ID
@@ -1156,11 +1156,11 @@
  * @uses bbp_get_forum_subscribers() To get the forum subscribers
  * @uses bbp_get_topic_author_display_name() To get the topic author's display name
  * @uses do_action() Calls 'bbp_pre_notify_forum_subscribers' with the topic id,
- *                    forum id and user id
+ *                    forum id and user id's
  * @uses apply_filters() Calls 'bbp_forum_subscription_mail_message' with the
- *                    message, topic id, forum id and user id
+ *                    message, topic id and forum id
  * @uses apply_filters() Calls 'bbp_forum_subscription_mail_title' with the
- *                    topic title, topic id, forum id and user id
+ *                    blog name, topic title, topic id  and forum id
  * @uses apply_filters() Calls 'bbp_forum_subscription_mail_headers'
  * @uses get_userdata() To get the user data
  * @uses wp_mail() To send the mail
@@ -1192,7 +1192,7 @@
 
 	/** Mail ******************************************************************/
 
-	// Remove filters from reply content and topic title to prevent content
+	// Remove filters from topic content and topic title to prevent content
 	// from being encoded with HTML entities, wrapped in paragraph tags, etc...
 	remove_all_filters( 'bbp_get_topic_content' );
 	remove_all_filters( 'bbp_get_topic_title'   );
@@ -1222,13 +1222,13 @@
 		$topic_url
 	);
 
-	$message = apply_filters( 'bbp_forum_subscription_mail_message', $message, $topic_id, $forum_id, $user_id );
+	$message = apply_filters( 'bbp_forum_subscription_mail_message', $message, $topic_id, $forum_id );
 	if ( empty( $message ) ) {
 		return;
 	}
 
 	// For plugins to filter titles per reply/topic/user
-	$subject = apply_filters( 'bbp_forum_subscription_mail_title', '[' . $blog_name . '] ' . $topic_title, $topic_id, $forum_id, $user_id );
+	$subject = apply_filters( 'bbp_forum_subscription_mail_title', '[' . $blog_name . '] ' . $topic_title, $topic_id, $forum_id );
 	if ( empty( $subject ) ) {
 		return;
 	}