diff --git a/yuthon_hr_attendance/controllers/applet_attendance.py b/yuthon_hr_attendance/controllers/applet_attendance.py
index a9b76076d..ecde027fd 100644
--- a/yuthon_hr_attendance/controllers/applet_attendance.py
+++ b/yuthon_hr_attendance/controllers/applet_attendance.py
@@ -977,7 +977,7 @@ class AppletAttendance(Controller):
                     'current_meter':record.current_meter if record.current_meter != 'NaN' else 0.0
                 }
                 result.append(tvalue)
-        return json.dumps(result)
+        return json.dumps(result, allow_nan=False)
 
 
     @route('/yuthon/meter/dosage', methods=['POST'], type='http', auth='none', cors='*', csrf=False)