diff --git a/components/tachart/tachartutils.pas b/components/tachart/tachartutils.pas
index 26bb0e5401..84f78ad401 100644
--- a/components/tachart/tachartutils.pas
+++ b/components/tachart/tachartutils.pas
@@ -138,6 +138,8 @@ function PointDistY(const A, B: TPoint): Integer; inline;
 procedure Unused(const A1);
 procedure Unused(const A1, A2);
 
+procedure UpdateMinMax(AValue: Double; var AMin, AMax: Double);
+
 operator +(const A: TPoint; B: TSize): TPoint;
 
 implementation
@@ -300,6 +302,14 @@ begin
 end;
 {$HINTS ON}
 
+procedure UpdateMinMax(AValue: Double; var AMin, AMax: Double);
+begin
+  if AValue < AMin then
+    AMin := AValue
+  else if AValue > AMax then
+    AMax := AValue;
+end;
+
 operator + (const A: TPoint; B: TSize): TPoint;
 begin
   Result.X := A.X + B.cx;
diff --git a/components/tachart/taseries.pas b/components/tachart/taseries.pas
index 31e36cf827..fc048a60dd 100644
--- a/components/tachart/taseries.pas
+++ b/components/tachart/taseries.pas
@@ -704,8 +704,7 @@ begin
   Result := inherited AddXY(X, Y, XLabel, Color);
 
   // Update max
-  if X > XGraphMax then XGraphMax := X;
-  if X < XGraphMin then XGraphMin := X;
+  UpdateMinMax(X, FXGraphMin, FXGraphMax);
   if Y > YGraphMax then begin
     YGraphMax := Y;
     XOfYGraphMax := X;
@@ -915,16 +914,14 @@ begin
   XGraphMin := MaxDouble;
   for i := 0 to Count - 1 do begin
     Val := PChartCoord(FCoordList.Items[i])^.x;
-    if Val > XGraphMax then XGraphMax := Val;
-    if Val < XGraphMin then XGraphMin := Val;
+    UpdateMinMax(Val, FXGraphMin, FXGraphMax);
   end;
 
   YGraphMax := MinDouble;
   YGraphMin := MaxDouble;
   for i:=0 to Count-1 do begin
     Val := PChartCoord(FCoordList.Items[i])^.y;
-    if Val > YGraphMax then YGraphMax := Val;
-    if Val < YGraphMin then YGraphMin := Val;
+    UpdateMinMax(Val, FYGraphMin, FYGraphMax);
   end;
 
   UpdateParentChart;
@@ -1437,10 +1434,8 @@ begin
   Result := inherited AddXY(X, Y, XLabel, Color);
 
   // Update max
-  if X > XGraphMax then XGraphMax := X;
-  if X < XGraphMin then XGraphMin := X;
-  if Y > YGraphMax then YGraphMax := Y;
-  if Y < YGraphMin then YGraphMin := Y;
+  UpdateMinMax(X, FXGraphMin, FXGraphMax);
+  UpdateMinMax(Y, FYGraphMin, FYGraphMax);
 
   UpdateParentChart;
 end;