diff --git a/lib/entity_widgets/history_chart/combined_history_chart.dart b/lib/entity_widgets/history_chart/combined_history_chart.dart
index d1c3610..42d3b78 100644
--- a/lib/entity_widgets/history_chart/combined_history_chart.dart
+++ b/lib/entity_widgets/history_chart/combined_history_chart.dart
@@ -19,6 +19,12 @@ class _CombinedHistoryChartWidgetState extends State<CombinedHistoryChartWidget>
   int _selectedId = -1;
   List<charts.Series<CombinedEntityStateHistoryMoment, DateTime>> _parsedHistory;
 
+  @override
+  void initState() {
+    // TODO: implement initState
+    super.initState();
+  }
+
   @override
   Widget build(BuildContext context) {
     _parsedHistory = _parseHistory();
@@ -28,11 +34,11 @@ class _CombinedHistoryChartWidgetState extends State<CombinedHistoryChartWidget>
     if ((_selectedId > -1) && (_parsedHistory != null) && (_parsedHistory.first.data.length >= (_selectedId + 1))) {
       selectedTime = _parsedHistory.first.data[_selectedId].startTime;
       _parsedHistory.where((item) { return item.id == "state"; }).forEach((item) {
-        selectedStates.add("${item.data[_selectedId].state}");
+        selectedStates.add(item.data[_selectedId].state);
         colorIndexes.add(item.data[_selectedId].colorId);
       });
       _parsedHistory.where((item) { return item.id == "value"; }).forEach((item) {
-        selectedStates.add("${item.data[_selectedId].value}");
+        selectedStates.add("${item.data[_selectedId].value ?? '-'}");
         colorIndexes.add(item.data[_selectedId].colorId);
       });
     }
@@ -101,10 +107,11 @@ class _CombinedHistoryChartWidgetState extends State<CombinedHistoryChartWidget>
         DateTime endTime;
         bool hiddenLine;
         double value;
+        double previousValue = 0.0;
         value = _parseToDouble(stateData["attributes"]["$attrName"]);
         bool hiddenDot = (value == null);
         if (hiddenDot && i > 0) {
-          value = data[i-1].value;
+          previousValue = data[i-1].value ?? data[i-1].previousValue;
         }
         if (i < (widget.rawHistory.length - 1)) {
           endTime = DateTime.tryParse(widget.rawHistory[i+1]["last_updated"])?.toLocal();
@@ -114,9 +121,9 @@ class _CombinedHistoryChartWidgetState extends State<CombinedHistoryChartWidget>
           hiddenLine = hiddenDot;
           endTime = now;
         }
-        data.add(CombinedEntityStateHistoryMoment(value, hiddenDot, hiddenLine, stateData["state"], startTime, endTime, i, colorIdCounter));
+        data.add(CombinedEntityStateHistoryMoment(value, previousValue, hiddenDot, hiddenLine, stateData["state"], startTime, endTime, i, colorIdCounter));
       }
-      data.add(CombinedEntityStateHistoryMoment(data.last.value, data.last.hiddenDot, data.last.hiddenLine, data.last.state, now, null, widget.rawHistory.length, colorIdCounter));
+      data.add(CombinedEntityStateHistoryMoment(data.last.value, data.last.previousValue, data.last.hiddenDot, data.last.hiddenLine, data.last.state, now, null, widget.rawHistory.length, colorIdCounter));
       numericDataLists.addAll({attrName: data});
       colorIdCounter += 1;
     });
@@ -142,7 +149,7 @@ class _CombinedHistoryChartWidgetState extends State<CombinedHistoryChartWidget>
             },
           strokeWidthPxFn: (CombinedEntityStateHistoryMoment historyMoment, __) => historyMoment.hiddenLine ? 0.0 : 2.0,
           domainFn: (CombinedEntityStateHistoryMoment historyMoment, _) => historyMoment.startTime,
-          measureFn: (CombinedEntityStateHistoryMoment historyMoment, _) => historyMoment.value ?? 0,
+          measureFn: (CombinedEntityStateHistoryMoment historyMoment, _) => historyMoment.value ?? historyMoment.previousValue,
           data: dataList,
           /*domainLowerBoundFn: (CombinedEntityStateHistoryMoment historyMoment, _) => historyMoment.time.subtract(Duration(hours: 1)),
           domainUpperBoundFn: (CombinedEntityStateHistoryMoment historyMoment, _) => historyMoment.time.add(Duration(hours: 1)),*/
@@ -254,7 +261,7 @@ class CombinedHistoryControlWidget extends StatelessWidget {
     for (int i = 0; i < selectedStates.length; i++) {
       children.add(
           Text(
-            "${selectedStates[i]}",
+            "${selectedStates[i] ?? '-'}",
             textAlign: TextAlign.right,
             style: TextStyle(
                 fontWeight: FontWeight.bold,
@@ -292,11 +299,12 @@ class CombinedEntityStateHistoryMoment {
   final DateTime startTime;
   final DateTime endTime;
   final double value;
+  final double previousValue;
   final int id;
   final int colorId;
   final String state;
   final bool hiddenDot;
   final bool hiddenLine;
 
-  CombinedEntityStateHistoryMoment(this.value, this.hiddenDot, this.hiddenLine, this.state, this.startTime, this.endTime,  this.id, this.colorId);
+  CombinedEntityStateHistoryMoment(this.value, this.previousValue, this.hiddenDot, this.hiddenLine, this.state, this.startTime, this.endTime,  this.id, this.colorId);
 }
diff --git a/lib/entity_widgets/history_chart/numeric_state_history_chart.dart b/lib/entity_widgets/history_chart/numeric_state_history_chart.dart
index ef40742..25f096f 100644
--- a/lib/entity_widgets/history_chart/numeric_state_history_chart.dart
+++ b/lib/entity_widgets/history_chart/numeric_state_history_chart.dart
@@ -34,7 +34,7 @@ class _NumericStateHistoryChartWidgetState extends State<NumericStateHistoryChar
       children: <Widget>[
         HistoryControlWidget(
           selectedTimeStart: selectedTime,
-          selectedState: "$selectedState",
+          selectedState: "${selectedState ?? '-'}",
           onPrevTap: () => _selectPrev(),
           onNextTap: () => _selectNext(),
           colorIndex: -1,
@@ -72,9 +72,22 @@ class _NumericStateHistoryChartWidgetState extends State<NumericStateHistoryChar
     for (var i = 0; i < widget.rawHistory.length; i++) {
       var stateData = widget.rawHistory[i];
       DateTime time = DateTime.tryParse(stateData["last_updated"])?.toLocal();
-      data.add(NumericEntityStateHistoryMoment(double.tryParse(stateData["state"]), time, i));
+      double value = double.tryParse(stateData["state"]);
+      double previousValue = 0.0;
+      bool hiddenDot = (value == null);
+      bool hiddenLine;
+      if (hiddenDot && i > 0) {
+        previousValue = data[i-1].value ?? data[i-1].previousValue;
+      }
+      if (i < (widget.rawHistory.length - 1)) {
+        double nextValue = double.tryParse(widget.rawHistory[i+1]["state"]);
+        hiddenLine = (nextValue == null || hiddenDot);
+      } else {
+        hiddenLine = hiddenDot;
+      }
+      data.add(NumericEntityStateHistoryMoment(value, previousValue, hiddenDot, hiddenLine, time, i));
     }
-    data.add(NumericEntityStateHistoryMoment(data.last.value, now, widget.rawHistory.length));
+    data.add(NumericEntityStateHistoryMoment(data.last.value, data.last.previousValue,  data.last.hiddenDot, data.last.hiddenLine, now, widget.rawHistory.length));
     if (_selectedId == -1) {
       _selectedId = 0;
     }
@@ -83,9 +96,18 @@ class _NumericStateHistoryChartWidgetState extends State<NumericStateHistoryChar
         id: 'State',
         colorFn: (NumericEntityStateHistoryMoment historyMoment, __) => EntityColors.chartHistoryStateColor("on", -1),
         domainFn: (NumericEntityStateHistoryMoment historyMoment, _) => historyMoment.time,
-        measureFn: (NumericEntityStateHistoryMoment historyMoment, _) => historyMoment.value,
+        measureFn: (NumericEntityStateHistoryMoment historyMoment, _) => historyMoment.value ?? historyMoment.previousValue,
         data: data,
-        radiusPxFn: (NumericEntityStateHistoryMoment historyMoment, __) => (historyMoment.id == _selectedId) ? 5.0 : 1.0,
+        strokeWidthPxFn: (NumericEntityStateHistoryMoment historyMoment, __) => historyMoment.hiddenLine ? 0.0 : 2.0,
+        radiusPxFn: (NumericEntityStateHistoryMoment historyMoment, __) {
+          if (historyMoment.hiddenDot) {
+            return 0.0;
+          } else if (historyMoment.id == _selectedId) {
+            return 5.0;
+          } else {
+            return 1.0;
+          }
+        },
       )
     ];
   }
@@ -126,7 +148,10 @@ class _NumericStateHistoryChartWidgetState extends State<NumericStateHistoryChar
 class NumericEntityStateHistoryMoment {
   final DateTime time;
   final double value;
+  final double previousValue;
   final int id;
+  final bool hiddenDot;
+  final bool hiddenLine;
 
-  NumericEntityStateHistoryMoment(this.value, this.time,  this.id);
+  NumericEntityStateHistoryMoment(this.value, this.previousValue, this.hiddenDot, this.hiddenLine, this.time,  this.id);
 }
\ No newline at end of file
diff --git a/lib/entity_widgets/history_chart/simple_state_history_chart.dart b/lib/entity_widgets/history_chart/simple_state_history_chart.dart
index 3d7fcd2..b2a8ccf 100644
--- a/lib/entity_widgets/history_chart/simple_state_history_chart.dart
+++ b/lib/entity_widgets/history_chart/simple_state_history_chart.dart
@@ -182,7 +182,7 @@ class HistoryControlWidget extends StatelessWidget {
                 child: Padding(
                   padding: EdgeInsets.only(right: 10.0),
                   child: Text(
-                    "$selectedState",
+                    "${selectedState ?? '-'}",
                     textAlign: TextAlign.right,
                     style: TextStyle(
                         fontWeight: FontWeight.bold,