diff --git a/services/comms/guest-name-job.yaml b/services/comms/guest-name-job.yaml
index 6179967..156617d 100644
--- a/services/comms/guest-name-job.yaml
+++ b/services/comms/guest-name-job.yaml
@@ -7,6 +7,7 @@ metadata:
 spec:
   schedule: "*/1 * * * *"
   suspend: false
+  concurrencyPolicy: Forbid
   successfulJobsHistoryLimit: 1
   failedJobsHistoryLimit: 1
   jobTemplate:
@@ -321,7 +322,8 @@ spec:
                                       if not new:
                                           continue
                                       cur.execute(
-                                          "INSERT INTO profiles (user_id, displayname, full_user_id) VALUES (%s, %s, %s)",
+                                          "INSERT INTO profiles (user_id, displayname, full_user_id) VALUES (%s, %s, %s) "
+                                          "ON CONFLICT (full_user_id) DO UPDATE SET displayname = EXCLUDED.displayname",
                                           (localpart, new, full_user_id),
                                       )
                       finally: