diff --git a/backend/app/api/quality.py b/backend/app/api/quality.py
index d7102b1..8427671 100644
--- a/backend/app/api/quality.py
+++ b/backend/app/api/quality.py
@@ -65,12 +65,10 @@ async def list_quality(
         query = query.where(QualityRecord.coil_no.ilike(f"%{coil_no}%"))
     if overall_grade:
         query = query.where(QualityRecord.overall_grade == overall_grade)
-    _sd = _parse_dt(start_date)
-    if _sd:
-        query = query.where(QualityRecord.created_at >= _sd)
-    _ed = _parse_dt(end_date)
-    if _ed:
-        query = query.where(QualityRecord.created_at <= _ed)
+    if start_date:
+        query = query.where(QualityRecord.created_at >= start_date)
+    if end_date:
+        query = query.where(QualityRecord.created_at <= end_date)
 
     total  = (await db.execute(select(func.count()).select_from(query.subquery()))).scalar()
     result = await db.execute(query.offset((page - 1) * page_size).limit(page_size))