diff --git a/src/sentry/uptime/consumers/tasks.py b/src/sentry/uptime/consumers/tasks.py
index 4591a4b520c5b9..1650f57e93bb8a 100644
--- a/src/sentry/uptime/consumers/tasks.py
+++ b/src/sentry/uptime/consumers/tasks.py
@@ -97,7 +97,6 @@ def process_uptime_backlog(subscription_id: str, attempt: int = 1):
         cluster.zrem(backlog_key, result_json)
         metrics.incr("uptime.backlog.removed", amount=1, sample_rate=1.0, tags=metric_tags)
         expected_next_ms += subscription_interval_ms
-        last_update_ms = result["scheduled_check_time_ms"]
         processed_count += 1
 
     # If we've hit max attempts process all remaining with backfill
@@ -119,6 +118,7 @@ def process_uptime_backlog(subscription_id: str, attempt: int = 1):
                 "uptime_region": result["region"],
                 "host_provider": host_provider,
             }
+            last_update_ms = int(cluster.get(last_update_key) or 0)
             create_backfill_misses(
                 detector,
                 subscription,