diff --git a/tf/modules/monitoring/sql-backup-failure-alert.tf b/tf/modules/monitoring/sql-backup-failure-alert.tf
index b8922f7c9..de0e14acc 100644
--- a/tf/modules/monitoring/sql-backup-failure-alert.tf
+++ b/tf/modules/monitoring/sql-backup-failure-alert.tf
@@ -28,7 +28,7 @@ resource "google_monitoring_alert_policy" "alert_policy_sql_logical_backup_failu
       aggregations {
         cross_series_reducer = "REDUCE_COUNT"
         per_series_aligner = "ALIGN_COUNT"
-        group_by_fields = "container_name"
+        group_by_fields = ["container_name"]
       }
       trigger {
         count = 1