diff --git a/hubzilla/addon/vs01/vs01_spool.php b/hubzilla/addon/vs01/vs01_spool.php
index 6009526..f7b75c7 100644
--- a/hubzilla/addon/vs01/vs01_spool.php
+++ b/hubzilla/addon/vs01/vs01_spool.php
@@ -163,7 +163,8 @@ function vs01_get_participant_id($association_slug) {
     // The channel name IS the Placekey for SASE participants.
     $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] ?? '');
 }
 
 // ---------------------------------------------------------------------------