diff --git a/phpBB/includes/functions_posting.php b/phpBB/includes/functions_posting.php
index 32206df868..11a5067ef9 100644
--- a/phpBB/includes/functions_posting.php
+++ b/phpBB/includes/functions_posting.php
@@ -2607,7 +2607,7 @@ function submit_post($mode, $subject, $username, $topic_type, &$poll, &$data, $u
 		// If a username was supplied or the poster is a guest, we will use the supplied username.
 		// Doing it this way we can use "...post by guest-username..." in notifications when
 		// "guest-username" is supplied or ommit the username if it is not.
-		$username = ($username || !$user->data['is_registered']) ? $username : $user->data['username'];
+		$username = ($username !== '' || !$user->data['is_registered']) ? $username : $user->data['username'];
 		user_notification($mode, $subject, $data['topic_title'], $data['forum_name'], $data['forum_id'], $data['topic_id'], $data['post_id'], $username);
 	}