diff --git a/src/db.rs b/src/db.rs
index a49a4a2..ac5be09 100644
--- a/src/db.rs
+++ b/src/db.rs
@@ -170,6 +170,7 @@ ON
   al.macaddr = mtn.macaddr
 WHERE
   mtn.nickname IS NULL
+  AND al.erfda > NOW() - INTERVAL 30 MINUTE
 ORDER BY
   al.erfda DESC
 ;