diff --git a/components/tachart/taseries.pas b/components/tachart/taseries.pas
index 3dc6389528..106c683d92 100644
--- a/components/tachart/taseries.pas
+++ b/components/tachart/taseries.pas
@@ -353,6 +353,7 @@ type
     FSeries: TChartSeries;
   public
     constructor Create(ASeries: TChartSeries);
+    procedure Forget; override;
     procedure Notify; override;
   end;
 
@@ -363,6 +364,12 @@ begin
   FSeries := ASeries;
 end;
 
+procedure TChartSeriesListener.Forget;
+begin
+  inherited Forget;
+  FSeries.FSource := nil;
+end;
+
 procedure TChartSeriesListener.Notify;
 begin
   FSeries.UpdateParentChart;
@@ -713,13 +720,11 @@ end;
 procedure TLineSeries.SetXValue(AIndex: Integer; AValue: Double);
 begin
   ListSource.SetXValue(AIndex, AValue);
-  UpdateParentChart;
 end;
 
 procedure TLineSeries.SetYValue(AIndex: Integer; AValue: Double);
 begin
-  ListSource.SetXValue(AIndex, AValue);
-  UpdateParentChart;
+  ListSource.SetYValue(AIndex, AValue);
 end;
 
 function TLineSeries.GetXImgValue(AIndex: Integer): Integer;
diff --git a/components/tachart/tasources.pas b/components/tachart/tasources.pas
index 8e9a94d01c..c8b318544e 100644
--- a/components/tachart/tasources.pas
+++ b/components/tachart/tasources.pas
@@ -24,8 +24,9 @@ type
   private
     FIsListening: Boolean;
   public
+    procedure Forget; virtual;
     procedure Notify; virtual; abstract;
-    property IsListening: Boolean read FIsListening write FIsListening;
+    property IsListening: Boolean read FIsListening;
   end;
 
   { TCustomChartSource }
@@ -193,7 +194,7 @@ var
   i: Integer;
 begin
   for i := 0 to High(FListeners) do
-    FListeners[i].IsListening := false;
+    FListeners[i].Forget;
   FListeners := nil;
   inherited Destroy;
 end;
@@ -252,7 +253,7 @@ begin
     raise EListenerError.Create('Listener subscribed twice');
   if FindListener(AListener) >= 0 then
     raise EListenerError.Create('Duplicate listener');
-  AListener.IsListening := true;
+  AListener.FIsListening := true;
   SetLength(FListeners, Length(FListeners) + 1);
   FListeners[High(FListeners)] := AListener;
 end;
@@ -263,7 +264,7 @@ var
 begin
   if not AListener.IsListening then
     raise EListenerError.Create('Listener not subscribed');
-  AListener.IsListening := false;
+  AListener.FIsListening := false;
   j := FindListener(AListener);
   if j < 0 then
     raise EListenerError.Create('Listener not found');
@@ -676,5 +677,12 @@ begin
   Notify;
 end;
 
+{ TListener }
+
+procedure TListener.Forget;
+begin
+  FIsListening := false;
+end;
+
 end.