diff --git privatemsg.module privatemsg.module
index 808e3e0..1a1a922 100644
--- privatemsg.module
+++ privatemsg.module
@@ -1020,7 +1020,7 @@ function privatemsg_sql_list(&$fragments, $account, $argument = 'list') {
                                                             WHERE pmia.type = 'user' AND pmia.thread_id = pmi.thread_id AND pmia.recipient <> %d), ',') AS participants";
     }
     else {
-      $fragments['select'][]      = "(SELECT GROUP_CONCAT(DISTINCT pmia.recipient SEPARATOR ',')
+      $fragments['select'][]      = "(SELECT GROUP_CONCAT(DISTINCT CONCAT(pmia.type, '_', pmia.recipient) SEPARATOR ',')
                                                             FROM {pm_index} pmia
                                                             WHERE pmia.type = 'user' AND pmia.thread_id = pmi.thread_id AND pmia.recipient <> %d) AS participants";
     }