diff --git a/app/Services/HR/AttendanceService.php b/app/Services/HR/AttendanceService.php
index d5f66d22..cde236a8 100644
--- a/app/Services/HR/AttendanceService.php
+++ b/app/Services/HR/AttendanceService.php
@@ -357,7 +357,7 @@ public function getEmployeeMonthlySummary(int $year, int $month): array
                 'user_id',
                 'status',
                 DB::raw('COUNT(*) as cnt'),
-                DB::raw("SUM(CAST(JSON_UNQUOTE(JSON_EXTRACT(json_details, '$.work_minutes')) AS UNSIGNED)) as total_minutes")
+                DB::raw("SUM(GREATEST(0, COALESCE(CAST(JSON_UNQUOTE(JSON_EXTRACT(json_details, '$.work_minutes')) AS SIGNED), 0))) as total_minutes")
             )
             ->groupBy('user_id', 'status')
             ->get();
@@ -409,7 +409,7 @@ public function getOvertimeAlerts(): array
             ->betweenDates($weekStart, $weekEnd)
             ->select(
                 'user_id',
-                DB::raw("SUM(CAST(JSON_UNQUOTE(JSON_EXTRACT(json_details, '$.work_minutes')) AS UNSIGNED)) as week_minutes")
+                DB::raw("SUM(GREATEST(0, COALESCE(CAST(JSON_UNQUOTE(JSON_EXTRACT(json_details, '$.work_minutes')) AS SIGNED), 0))) as week_minutes")
             )
             ->groupBy('user_id')
             ->having('week_minutes', '>=', 2880) // 48시간 = 2880분