diff --git a/components/fpspreadsheet/fpspreadsheet.pas b/components/fpspreadsheet/fpspreadsheet.pas
index bbb924600..a104ee11a 100755
--- a/components/fpspreadsheet/fpspreadsheet.pas
+++ b/components/fpspreadsheet/fpspreadsheet.pas
@@ -678,7 +678,8 @@ type
     { Formulas }
     procedure CalcFormulas;
     function  ReadRPNFormulaAsString(ACell: PCell): String;
-    function UseSharedFormula(ARow, ACol: Cardinal; ASharedFormulaBase: PCell): PCell;
+    function UseSharedFormula(ARow, ACol: Cardinal; ASharedFormulaBase: PCell): PCell; overload;
+    procedure UseSharedFormula(ACellRangeStr: String; ASharedFormulaBase: PCell); overload;
 
     { Data manipulation methods - For Cells }
     procedure CopyCell(AFromRow, AFromCol, AToRow, AToCol: Cardinal; AFromWorksheet: TsWorksheet);
@@ -2956,6 +2957,33 @@ begin
       [GetCellString(ARow, ACol)]);
 end;
 
+{@@
+  Uses the formula defined in cell "ASharedFormulaBase" as a shared formula in
+  all cells of the given cell range.
+
+  @param ACellRangeStr       Range of cells which will use the shared formula.
+                             The range is given as a string in Excel notation,
+                             such as A1:B5, or A1
+  @param ASharedFormulaBase  Cell containing the formula to be shared
+}
+procedure TsWorksheet.UseSharedFormula(ACellRangeStr: String; ASharedFormulaBase: PCell);
+var
+  r, c, r1, c1, r2, c2: Cardinal;
+  ok: Boolean;
+begin
+  if pos(':', ACellRangeStr) = 0 then
+  begin
+    ok := ParseCellString(ACellRangeStr, r1, c1);
+    r2 := r1;
+    c2 := c1;
+  end else
+    ok := ParseCellRangeString(ACellRangeStr, r1, c1, r2, c2);
+  if ok then
+    for r := r1 to r2 do
+      for c := c1 to c2 do
+        UseSharedFormula(r, c, ASharedFormulaBase);
+end;
+
 {@@
   Writes UTF-8 encoded text to a cell.
 
diff --git a/components/fpspreadsheet/fpsutils.pas b/components/fpspreadsheet/fpsutils.pas
index e11f63887..a1fc9f826 100644
--- a/components/fpspreadsheet/fpsutils.pas
+++ b/components/fpspreadsheet/fpsutils.pas
@@ -64,7 +64,9 @@ function ParseIntervalString(const AStr: string;
   out ADirection: TsSelectionDirection): Boolean;
 function ParseCellRangeString(const AStr: string;
   out AFirstCellRow, AFirstCellCol, ALastCellRow, ALastCellCol: Cardinal;
-  out AFlags: TsRelFlags): Boolean;
+  out AFlags: TsRelFlags): Boolean; overload;
+function ParseCellRangeString(const AStr: string;
+  out AFirstCellRow, AFirstCellCol, ALastCellRow, ALastCellCol: Cardinal): Boolean; overload;
 function ParseCellString(const AStr: string;
   out ACellRow, ACellCol: Cardinal; out AFlags: TsRelFlags): Boolean; overload;
 function ParseCellString(const AStr: string;
@@ -76,7 +78,8 @@ function ParseCellColString(const AStr: string;
 
 function GetColString(AColIndex: Integer): String;
 function GetCellString(ARow,ACol: Cardinal; AFlags: TsRelFlags = [rfRelRow, rfRelCol]): String;
-function GetCellRangeString(ARow1, ACol1, ARow2, ACol2: Cardinal; AFlags: TsRelFlags): String;
+function GetCellRangeString(ARow1, ACol1, ARow2, ACol2: Cardinal;
+  AFlags: TsRelFlags = [rfRelRow, rfRelCol, rfRelRow2, rfRelCol2]): String;
 
 function GetErrorValueStr(AErrorValue: TsErrorValue): String;
 
@@ -427,6 +430,26 @@ begin
 end;
 
 
+{@@
+  Parses strings like A5:C10 into a range selection information.
+  Information on relative/absolute cells is ignored.
+
+  @param  AStr           Cell range string, such as A5:C10
+  @param  AFirstCellRow  Row index of the top/left cell of the range (output)
+  @param  AFirstCellCol  Column index of the top/left cell of the range (output)
+  @param  ALastCellRow   Row index of the bottom/right cell of the range (output)
+  @param  ALastCellCol   Column index of the bottom/right cell of the range (output)
+  @return                false if the string is not a valid cell range
+}
+function ParseCellRangeString(const AStr: string;
+  out AFirstCellRow, AFirstCellCol, ALastCellRow, ALastCellCol: Cardinal): Boolean;
+var
+  flags: TsRelFlags;
+begin
+  Result := ParseCellRangeString(AStr, AFirstCellRow, AFirstCellCol, ALastCellRow, ALastCellCol, flags);
+end;
+
+
 {@@
   Parses a cell string, like 'A1' into zero-based column and row numbers
   Note that there can be several letters to address for more than 26 columns.
@@ -647,7 +670,8 @@ end;
   @example ARow1 = 0, ACol1 = 0, ARow = 2, ACol = 1, AFlags = [rfRelRow, rfRelRow2]
            --> $A1:$B3
 }
-function GetCellRangeString(ARow1, ACol1, ARow2, ACol2: Cardinal; AFlags: TsRelFlags): String;
+function GetCellRangeString(ARow1, ACol1, ARow2, ACol2: Cardinal;
+  AFlags: TsRelFlags = [rfRelRow, rfRelCol, rfRelRow2, rfRelCol2]): String;
 begin
   Result := Format('%s%s%s%d:%s%s%s%d', [
     RELCHAR[rfRelCol in AFlags], GetColString(ACol1),
diff --git a/components/fpspreadsheet/xlsbiff2.pas b/components/fpspreadsheet/xlsbiff2.pas
index 11fdca270..bd16f4e5b 100755
--- a/components/fpspreadsheet/xlsbiff2.pas
+++ b/components/fpspreadsheet/xlsbiff2.pas
@@ -790,7 +790,9 @@ end;
 
 { Reads the cell coordiantes of the top/left cell of a range using a shared formula.
   This cell contains the rpn token sequence of the formula.
-  Is overridden because BIFF2 has 1 byte for column. }
+  Is overridden because BIFF2 has 1 byte for column.
+  Code is not called for shared formulas (which are not supported by BIFF2), but
+  maybe for array formulas. }
 procedure TsSpreadBIFF2Reader.ReadRPNSharedFormulaBase(AStream: TStream;
   out ARow, ACol: Cardinal);
 begin
diff --git a/components/fpspreadsheet/xlscommon.pas b/components/fpspreadsheet/xlscommon.pas
index e35f62069..56764960c 100644
--- a/components/fpspreadsheet/xlscommon.pas
+++ b/components/fpspreadsheet/xlscommon.pas
@@ -535,7 +535,8 @@ type
     procedure WriteSelections(AStream: TStream; ASheet: TsWorksheet);
     // Writes out a shared formula
     procedure WriteSharedFormula(AStream: TStream; ACell: PCell); virtual;
-    procedure WriteSharedFormulaRange(AStream: TStream; const ARange: TRect); virtual;
+    procedure WriteSharedFormulaRange(AStream: TStream;
+      AFirstRow, AFirstCol, ALastRow, ALastCol: Cardinal); virtual;
     procedure WriteSheetPR(AStream: TStream);
     procedure WriteStringRecord(AStream: TStream; AString: String); virtual;
     // Writes cell content received by workbook in OnNeedCellData event
@@ -2882,8 +2883,7 @@ end;
   the formulas in each cell. In BIFF2 WriteSharedFormula must not do anything. }
 procedure TsSpreadBIFFWriter.WriteSharedFormula(AStream: TStream; ACell: PCell);
 var
-  range: TRect;
-  node: TAVLTreeNode;
+  r, c, r1, r2, c1, c2: Cardinal;
   cell: PCell;
   RPNLength: word;
   recordSizePos: Int64;
@@ -2892,32 +2892,29 @@ var
   i: Integer;
 begin
   // Determine cell range covered by the shared formula in ACell.
-  range := Rect(-1, -1, -1, -1);
-  node := FWorksheet.Cells.FindLowest;
-  while Assigned(node) do begin
-    cell := PCell(node.Data);
-    if cell.SharedFormulaBase = ACell then begin
-      // Nodes are ordered along rows --> the first cell met must be the left border of the range
-      if range.Left = -1 then
-        range.Left := cell.Col
-      else
-      if cell.Col < range.Left then begin
-        FWorkbook.AddErrorMsg('Non-rectangular cell range covered by shared formula in cell %s',
-          [GetCellString(ACell^.Row, ACell^.Col)]);
-        exit;
-      end;
-      // The right border of the range must have the max col index
-      if range.Right = -1 then
-        range.Right := cell.Col
-      else if cell.Col > range.Right then
-        range.Right := cell.Col;
-      // The first cell met must be the top border of the range
-      if range.Top = -1 then
-        range.Top := Cell.Row;
-      // dto. with bottom border
-      range.Bottom := Cell.Row;
-    end;
-    node := FWorksheet.Cells.FindSuccessor(node);
+  // Find range of cells using this shared formula
+  r1 := ACell^.Row;   r2 := r1;
+  c1 := ACell^.Col;   c2 := c1;
+  r := r1;
+  c := c1;
+  while c <= FWorksheet.GetLastColIndex do
+  begin
+    cell := FWorksheet.FindCell(r, c);
+    if (cell <> nil) and (cell^.SharedFormulaBase = ACell^.SharedFormulaBase) then
+      c2 := c
+    else
+      break;
+    inc(c);
+  end;
+  c := c1;
+  while r <= FWorksheet.GetLastRowIndex do
+  begin
+    cell := FWorksheet.FindCell(r, c);
+    if (cell <> nil) and (cell^.SharedFormulaBase <> ACell^.SharedFormulaBase) then
+      r2 := r
+    else
+      break;
+    inc(r);
   end;
 
   // Write BIFF record ID and size
@@ -2927,13 +2924,13 @@ begin
   startPos := AStream.Position;
 
   // Write borders of cell range covered by the formula
-  WriteSharedFormulaRange(AStream, range);
+  WriteSharedFormulaRange(AStream, r1, c1, r2, c2);
 
   // Not used
   AStream.WriteByte(0);
 
   // Number of existing formula records
-  AStream.WriteByte((range.Right-range.Left+1)*(range.Bottom-range.Top+1));
+  AStream.WriteByte((r2-r1+1) * (c2-c1+1));
 
   // Copy the formula (we don't want to overwrite the cell formulas)
   // and adjust relative references
@@ -2956,16 +2953,20 @@ end;
   Valid for BIFF5 and BIFF8 - BIFF8 writes 8-bit column index as well.
   No need for BIFF2 which does not support shared formulas. }
 procedure TsSpreadBIFFWriter.WriteSharedFormulaRange(AStream: TStream;
-  const ARange: TRect);
+  AFirstRow, AFirstCol, ALastRow, ALastCol: Cardinal);
+var
+  c: Word;
 begin
   // Index to first row
-  AStream.WriteWord(WordToLE(ARange.Top));
+  AStream.WriteWord(WordToLE(AFirstRow));
   // Index to last row
-  AStream.WriteWord(WordToLE(ARange.Bottom));
+  AStream.WriteWord(WordToLE(ALastRow));
   // Index to first column
-  AStream.WriteByte(Lo(ARange.Left));
+  c := Lo(AFirstCol);
+  AStream.WriteByte(Lo(c));
   // Index to last rcolumn
-  AStream.WriteByte(Lo(ARange.Right));
+  c := Lo(ALastCol);
+  AStream.WriteByte(Lo(c));
 end;
 
 
diff --git a/components/fpspreadsheet/xlsxooxml.pas b/components/fpspreadsheet/xlsxooxml.pas
index 14028b90d..d8a7390b5 100755
--- a/components/fpspreadsheet/xlsxooxml.pas
+++ b/components/fpspreadsheet/xlsxooxml.pas
@@ -2266,6 +2266,8 @@ end;
 
 procedure TsSpreadOOXMLWriter.WriteWorksheet(AWorksheet: TsWorksheet);
 begin
+  FWorksheet := AWorksheet;
+
   FCurSheetNum := Length(FSSheets);
   SetLength(FSSheets, FCurSheetNum + 1);
 
@@ -2499,16 +2501,69 @@ procedure TsSpreadOOXMLWriter.WriteFormula(AStream: TStream;
 var
   cellPosText: String;
   lStyleIndex: Integer;
+  r, c, r2, c2: Cardinal;
+  cell: PCell;
+  id: Cardinal;
 begin
   cellPosText := TsWorksheet.CellPosToText(ARow, ACol);
   lStyleIndex := GetStyleIndex(ACell);
 
-  AppendToStream(AStream, Format(
-    '<c r="%s" s="%d">' +
-      '<f>%s</f>' +
-    '</c>', [
-    CellPosText, lStyleIndex,
-    PrepareFormula(ACell^.FormulaValue)
+  // Cell uses a shared formula
+  if Assigned(ACell^.SharedFormulaBase) then begin
+    // Cell is base of the shared formula, i.e. contains the shared formula
+    if (ACell = ACell^.SharedFormulaBase) then
+    begin
+      // Find range of cells using this shared formula
+      r2 := ACell^.Row;
+      c2 := ACell^.Col;
+      c := c2;
+      r := r2;
+      while c <= FWorksheet.GetLastColIndex do
+      begin
+        cell := FWorksheet.FindCell(r, c);
+        if (cell <> nil) and (cell^.SharedFormulaBase = ACell^.SharedFormulaBase) then
+          c2 := c
+        else
+          break;
+        inc(c);
+      end;
+      c := ACell^.Col;
+      while r <= FWorksheet.GetLastRowIndex do
+      begin
+        cell := FWorksheet.FindCell(r, c);
+        if (cell <> nil) and (cell^.SharedFormulaBase <> ACell^.SharedFormulaBase) then
+          r2 := r
+        else
+          break;
+        inc(r);
+      end;
+
+      AppendToStream(AStream, Format(
+        '<c r="%s" s="%d">' +
+          '<f t="shared" ref="%s" si="%d">%s</f>' +
+        '</c>', [
+        CellPosText, lStyleIndex,
+        GetCellRangeString(ACell^.Row, ACell^.Col, r2, c2),
+        PtrInt(ACell),       // Use the cell pointer as ID of the shared formula
+        PrepareFormula(ACell^.FormulaValue)
+      ]));
+    end else
+      // Cell uses the shared formula
+      AppendToStream(AStream, Format(
+        '<c r="%s" s="%d">' +
+          '<f t="shared" si="%d" />' +
+        '</c>', [
+        CellPosText, lStyleIndex,
+        PtrInt(ACell^.SharedFormulaBase)   // ID of the shared formula
+      ]));
+  end else
+    // "normal" formula
+    AppendToStream(AStream, Format(
+      '<c r="%s" s="%d">' +
+        '<f>%s</f>' +
+      '</c>', [
+      CellPosText, lStyleIndex,
+      PrepareFormula(ACell^.FormulaValue)
     ]));
 end;