diff --git a/pandora_server/util/pandora_db.pl b/pandora_server/util/pandora_db.pl
index 0cd7cc9104..b472e468d5 100644
--- a/pandora_server/util/pandora_db.pl
+++ b/pandora_server/util/pandora_db.pl
@@ -166,7 +166,7 @@ sub pandora_purgedb ($$) {
 		$conf->{'_string_purge'} = 7;
 	}
 	# Update alert with last_fired older than today - time_threshold
-	my @templates = get_db_rows ($dbh, 'SELECT t1.id,t1.time_threshold FROM talert_templates t1 JOIN talert_template_modules t2 ON t1.id = t2.id_alert_template');
+	my @templates = get_db_rows ($dbh, 'SELECT t1.id,t1.time_threshold FROM talert_templates t1 WHERE EXISTS ( SELECT * FROM talert_template_modules t2 WHERE t1.id = t2.id_alert_template );');
 	foreach my $template(@templates) {
 		db_do($dbh, 'UPDATE talert_template_modules SET times_fired = 0 WHERE id_alert_template = ? AND times_fired > 0 AND last_fired < (? - ?)',$template->{'id'},time(),$template->{'time_threshold'});
 	}