diff --git a/hubzilla/addon/dsc01/dsc01_spool.php b/hubzilla/addon/dsc01/dsc01_spool.php
index 189736d..5db6c6c 100644
--- a/hubzilla/addon/dsc01/dsc01_spool.php
+++ b/hubzilla/addon/dsc01/dsc01_spool.php
@@ -123,7 +123,8 @@ function dsc01_get_participant_id() {
 
     $addr  = $r[0]['xchan_addr'] ?? '';
     $parts = explode('@', $addr);
-    return $parts[0] ?? '';
+    // Strip guest: prefix — Placekey is the channel name without the guest: qualifier.
+    return preg_replace('/^guest:/', '', $parts[0] ?? '');
 }
 
 // ---------------------------------------------------------------------------