diff --git a/components/fpspreadsheet/examples/other/chart/regressionchart_write_demo.lpr b/components/fpspreadsheet/examples/other/chart/regressionchart_write_demo.lpr
index 018b0fa91..9a42350a1 100644
--- a/components/fpspreadsheet/examples/other/chart/regressionchart_write_demo.lpr
+++ b/components/fpspreadsheet/examples/other/chart/regressionchart_write_demo.lpr
@@ -1,6 +1,6 @@
 program regressionchart_write_demo;
 
-{.$DEFINE DARK_MODE}
+{$mode objfpc}{$H+}
 
 uses
   SysUtils,
@@ -16,7 +16,7 @@ var
 begin
   book := TsWorkbook.Create;
   try
-    // worksheet
+    // Worksheet
     sheet := book.AddWorksheet('regression_test');
 
     // Enter data
@@ -28,10 +28,10 @@ begin
     sheet.WriteNumber(5, 0, 2.5);  sheet.WriteNumber(5, 1, 2.45);
     sheet.WriteNumber(6, 0, 3.1);  sheet.WriteNumber(6, 1, 3.3);
     sheet.WriteNumber(7, 0, 5.2);  sheet.WriteNumber(7, 1, 4.9);
-    sheet.WriteNumber(8, 0, 6.8);  sheet.WriteNumber(8, 1, 7.1);        // sheet.WriteChartColor(8, 2, $FF8080);
+    sheet.WriteNumber(8, 0, 6.8);  sheet.WriteNumber(8, 1, 7.1);
 
-    // Create chart: left/top in cell D4, 120 mm x 100 mm
-    ch := book.AddChart(sheet, 2, 3, 120, 100);
+    // Create chart: left/top in cell D4, 150 mm x 100 mm
+    ch := book.AddChart(sheet, 2, 3, 150, 100);
 
     // Chart properties
     ch.Border.Style := clsNoLine;
@@ -54,7 +54,7 @@ begin
     ser.Regression.Line.Color := scRed;
     ser.Regression.Line.Style := clsDash;
     ser.Regression.ForceYIntercept := true;  // not used by logarithmic, power
-    ser.Regression.YInterceptValue := 1.0;
+    ser.Regression.YInterceptValue := 1.0;   // dto.
     ser.Regression.PolynomialDegree := 2;
     ser.Regression.DisplayEquation := true;
     ser.Regression.DisplayRSquare := true;
diff --git a/components/fpspreadsheet/source/visual/fpspreadsheetchart.pas b/components/fpspreadsheet/source/visual/fpspreadsheetchart.pas
index 5be169785..7180550d7 100644
--- a/components/fpspreadsheet/source/visual/fpspreadsheetchart.pas
+++ b/components/fpspreadsheet/source/visual/fpspreadsheetchart.pas
@@ -244,6 +244,8 @@ begin
     APen.Style := psDashDotDot
 end;
 
+{ Converts an fps format string (e.g. '0.000') to a format string usable in
+  the Format() command (e.g. '%.3f') }
 function Convert_NumFormatStr_to_FormatStr(ANumFormat: String): String;
 var
   isPercent: Boolean = false;
@@ -1899,7 +1901,7 @@ begin
       s := s + ser.EquationText.
         X(AWorkbookSeries.Regression.Equation.XName).
         Y(AWorkbookSeries.Regression.Equation.YName).
-        NumFormat('%.3f'). // to do: convert from AWorkbookSeries.Regression.Equation.NumberFormat
+        NumFormat(Convert_NumFormatStr_to_FormatStr(AWorkbookSeries.Regression.Equation.NumberFormat)).
         DecimalSeparator('.').
         TextFormat(tfHtml).
         Get;