diff --git a/src/lib/features/release-plans/release-plan-milestone.ts b/src/lib/features/release-plans/release-plan-milestone.ts
index fb95914d21..e2aaffa620 100644
--- a/src/lib/features/release-plans/release-plan-milestone.ts
+++ b/src/lib/features/release-plans/release-plan-milestone.ts
@@ -8,7 +8,7 @@ export interface ReleasePlanMilestone {
     startedAt?: Date;
     transitionCondition?: { intervalMinutes: number };
     strategies?: ReleasePlanMilestoneStrategy[];
-    progressionExecutedAt?: string;
+    progressionExecutedAt?: Date;
 }
 
 export type ReleasePlanMilestoneWriteModel = Omit<