diff --git a/lib/trigger/syncTriggerSchedule.ts b/lib/trigger/syncTriggerSchedule.ts
index f8bd63e..45e8905 100644
--- a/lib/trigger/syncTriggerSchedule.ts
+++ b/lib/trigger/syncTriggerSchedule.ts
@@ -37,6 +37,7 @@ export async function syncTriggerSchedule(
     await updateSchedule({
       scheduleId: existingScheduleId,
       cron: cronExpression,
+      externalId: taskId,
     });
     return existingScheduleId;
   }
diff --git a/lib/trigger/updateSchedule.ts b/lib/trigger/updateSchedule.ts
index 903c1c4..b34ea86 100644
--- a/lib/trigger/updateSchedule.ts
+++ b/lib/trigger/updateSchedule.ts
@@ -3,10 +3,12 @@ import { schedules } from "@trigger.dev/sdk";
 type UpdateScheduleParams = {
   scheduleId: string;
   cron: string;
+  externalId: string;
 };
 
 /**
- * Updates an existing Trigger.dev schedule with a new cron expression
+ * Updates an existing Trigger.dev schedule with a new cron expression.
+ * Includes externalId to prevent it from being cleared during updates.
  */
 export async function updateSchedule(
   params: UpdateScheduleParams
@@ -14,5 +16,6 @@ export async function updateSchedule(
   await schedules.update(params.scheduleId, {
     task: "customer-prompt-task",
     cron: params.cron,
+    externalId: params.externalId,
   });
 }