diff --git a/FrontendWebApi/ApiControllers/HistoryController.cs b/FrontendWebApi/ApiControllers/HistoryController.cs
index b45c3b4..8614dd5 100644
--- a/FrontendWebApi/ApiControllers/HistoryController.cs
+++ b/FrontendWebApi/ApiControllers/HistoryController.cs
@@ -102,7 +102,7 @@ namespace FrontendWebApi.ApiControllers
                 #endregion
 
                 #region get data from niagara
-                lhe.endtime = lhe.dateType == "today" ? lhe.starttime : lhe.dateType == "month" ? lhe.starttime.AddMonths(1) : lhe.endtime;
+                lhe.endtime = lhe.dateType == "today" ? lhe.starttime : lhe.dateType == "month" ? lhe.starttime.AddMonths(1).AddDays(-1) : lhe.endtime;
                 var startTimestamp = string.Format("{0}T00:00:00.000+08:00", lhe.starttime.ToString("yyyy-MM-dd"));
                 var endTimestamp = string.Format("{0}T23:59:59.000+08:00", lhe.endtime?.ToString("yyyy-MM-dd"));
                 var historyQueryFilter = $@"<obj is='obix: HistoryFilter'>