diff --git a/app/modules/employees/service.py b/app/modules/employees/service.py
index 8d30e6d..4c73ab6 100644
--- a/app/modules/employees/service.py
+++ b/app/modules/employees/service.py
@@ -896,7 +896,13 @@ def _evaluate_attendance_timing(branch: Branch | None, settings: BranchSettings
 def _attendance_duration_minutes(row: EmployeeAttendance) -> int | None:
     if not row.punch_in_utc or not row.punch_out_utc:
         return None
-    delta = row.punch_out_utc - row.punch_in_utc
+
+    punch_in_utc = _as_utc_aware(row.punch_in_utc)
+    punch_out_utc = _as_utc_aware(row.punch_out_utc)
+    if not punch_in_utc or not punch_out_utc:
+        return None
+
+    delta = punch_out_utc - punch_in_utc
     minutes = int(delta.total_seconds() // 60)
     return max(minutes, 0)