diff --git a/src/LTMPlot.cpp b/src/LTMPlot.cpp
index 596afebd2..ab6ac83a3 100644
--- a/src/LTMPlot.cpp
+++ b/src/LTMPlot.cpp
@@ -1226,7 +1226,7 @@ LTMPlot::setData(LTMSettings *set)
         // make start date always fall on a Monday
         if (settings->groupBy == LTM_WEEK) {
             int dow = settings->start.date().dayOfWeek(); // 1-7, where 1=monday
-            settings->start.date().addDays(dow-1*-1);
+            settings->start = QDateTime(settings->start.date().addDays(dow-1*-1));
         }
 
         // setup the xaxis at the bottom