diff --git a/lib/messageform.php b/lib/messageform.php
index 80e7716cda..acd30e3b38 100644
--- a/lib/messageform.php
+++ b/lib/messageform.php
@@ -141,7 +141,7 @@ class MessageForm extends Form
         unset($mutual_users);
 
         if (count($mutual) == 1) {
-            // TRANS Entry in drop-down selection box in direct-message inbox/outbox when no one is available to message.
+            // TRANS: Entry in drop-down selection box in direct-message inbox/outbox when no one is available to message.
             $mutual[0] = _('No mutual subscribers.');
         }