diff --git a/actions/approvesub.php b/actions/approvesub.php
index be07b6e877..5fbb2149bd 100644
--- a/actions/approvesub.php
+++ b/actions/approvesub.php
@@ -73,6 +73,7 @@ class ApprovesubAction extends Action
 
         if (empty($this->request)) {
             // TRANS: Client error displayed trying to approve subscription for a non-existing request.
+            // TRANS: %s is a user nickname.
             $this->clientError(sprintf(_('%s is not in the moderation queue for your subscriptions.'), $this->profile->nickname), 403);
         }