diff --git a/components/fpspreadsheet/source/common/fpscsv.pas b/components/fpspreadsheet/source/common/fpscsv.pas
index 59cc786bc..1f2516412 100644
--- a/components/fpspreadsheet/source/common/fpscsv.pas
+++ b/components/fpspreadsheet/source/common/fpscsv.pas
@@ -192,8 +192,8 @@ procedure TsCSVReader.ReadFromStream(AStream: TStream; APassword: String = '';
   AParams: TsStreamParams = []);
 var
   Parser: TCSVParser;
-  s: String;
   encoding: String;
+  s: String = '';
 begin
   Unused(AParams, APassword);
 
diff --git a/components/fpspreadsheet/source/common/fpsexprparser.pas b/components/fpspreadsheet/source/common/fpsexprparser.pas
index 4a9aac514..82e6c1f0d 100644
--- a/components/fpspreadsheet/source/common/fpsexprparser.pas
+++ b/components/fpspreadsheet/source/common/fpsexprparser.pas
@@ -1873,7 +1873,7 @@ var
   X: TsExprFloat;
   lCount: Integer;
   ID: TsExprIdentifierDef;
-  Args: TsExprArgumentArray;
+  Args: TsExprArgumentArray = nil;
   AI: Integer;
   optional: Boolean;
   token: String;
@@ -2185,7 +2185,7 @@ procedure TsExpressionParser.SetRPNFormula(const AFormula: TsRPNFormula);
     flags: TsRelFlags;
     ID: TsExprIdentifierDef;
     i, n: Integer;
-    args: TsExprArgumentArray;
+    args: TsExprArgumentArray = nil;
     sn, sn2: string;
     rng: TsCellRange;
   begin
@@ -4742,7 +4742,7 @@ var
   idx, idx1, idx2: Integer;
 begin
   AError := errOK;
-  SetLength(AData, BLOCKSIZE);
+  SetLength(AData{%H-}, BLOCKSIZE);
   n := 0;
   for i:=Low(Args) to High(Args) do
   begin
diff --git a/components/fpspreadsheet/source/common/fpshtmlutils.pas b/components/fpspreadsheet/source/common/fpshtmlutils.pas
index ac654b317..12b08a1c8 100644
--- a/components/fpspreadsheet/source/common/fpshtmlutils.pas
+++ b/components/fpspreadsheet/source/common/fpshtmlutils.pas
@@ -951,6 +951,7 @@ var
   len: Integer;
   nrtp: Integer;
 begin
+  ARichTextParams := nil;
   analyzer := TsHTMLAnalyzer.Create(AWorkbook as TsWorkbook, AFont, AHTMLText + '<end>');
   try
     analyzer.PreserveSpaces := true;
@@ -967,8 +968,7 @@ begin
       SetLength(ARichTextParams, nrtp);
       for j:=0 to nrtp-1 do
         ARichTextParams[j] := analyzer.RichTextParams[j];
-    end else
-      SetLength(ARichTextParams, 0);
+    end;
   finally
     analyzer.Free;
   end;
@@ -1162,7 +1162,7 @@ procedure TsHTMLComposer.GetFontsFromWorkbook(out AFonts: TsFontArray);
 var
   i: Integer;
 begin
-  SetLength(AFonts, Length(FRichTextParams));
+  SetLength(AFonts{%H-}, Length(FRichTextParams));
   for i:=0 to High(AFonts) do
     AFonts[i] := FWorkbook.GetFont(FRichTextParams[i].FontIndex);
 end;
diff --git a/components/fpspreadsheet/source/common/fpsnumformat.pas b/components/fpspreadsheet/source/common/fpsnumformat.pas
index d846d9138..71e6a7874 100644
--- a/components/fpspreadsheet/source/common/fpsnumformat.pas
+++ b/components/fpspreadsheet/source/common/fpsnumformat.pas
@@ -2573,7 +2573,7 @@ end;
 function TsNumFormatList.AddFormat(AFormatStr: String): Integer;
 var
   parser: TsNumFormatParser;
-  newSections: TsNumFormatSections;
+  newSections: TsNumFormatSections = nil;
   i: Integer;
 begin
   parser := TsNumFormatParser.Create(AFormatStr, FFormatSettings);
diff --git a/components/fpspreadsheet/source/common/fpsopendocument.pas b/components/fpspreadsheet/source/common/fpsopendocument.pas
index aba277611..68b3a5081 100644
--- a/components/fpspreadsheet/source/common/fpsopendocument.pas
+++ b/components/fpspreadsheet/source/common/fpsopendocument.pas
@@ -2172,7 +2172,6 @@ end;
 procedure TsSpreadOpenDocReader.ReadConditionalFormats(ANode: TDOMNode;
   AWorksheet: TsBasicWorksheet);
 var
-  sheet: TsWorksheet;
   childNode: TDOMNode;
   nodeName: String;
   s: String;
@@ -2184,7 +2183,6 @@ begin
   if ANode = nil then
     exit;
 
-  sheet := TsWorksheet(AWorksheet);
   ANode := ANode.FirstChild;
   while ANode <> nil do
   begin
@@ -2888,7 +2886,7 @@ var
   nodeName: String;
   cell: PCell;
   hyperlink: string;
-  rtParams: TsRichTextParams;
+  rtParams: TsRichTextParams = nil;
   idx: Integer;
   rtFntIndex, fntIndex: Integer;
   rtFnt, fnt: TsFont;
@@ -3827,7 +3825,8 @@ var
   fmt: TsCellFormat;
   ok: Boolean;
   condition: TsCFCondition;
-  param1, param2: String;
+  param1: String = '';
+  param2: String = '';
   op1, op2: Variant;
   sheet: TsWorksheet;
 begin
@@ -3939,8 +3938,8 @@ begin
   if not ok then
     exit;
 
-  if param1 = '' then VarClear(op1) else op1 := param1;
-  if param2 = '' then VarClear(op2) else op2 := param2;
+  if param1 = '' then VarClear(op1{%H-}) else op1 := param1;
+  if param2 = '' then VarClear(op2{%H-}) else op2 := param2;
   sheet.WriteConditionalCellFormat(ARange, condition, op1, op2, fmtIndex);
 end;
 
diff --git a/components/fpspreadsheet/source/common/fpspreadsheet.pas b/components/fpspreadsheet/source/common/fpspreadsheet.pas
index 83670f018..e4d8a48c9 100644
--- a/components/fpspreadsheet/source/common/fpspreadsheet.pas
+++ b/components/fpspreadsheet/source/common/fpspreadsheet.pas
@@ -1255,15 +1255,13 @@ function TsWorksheet.BuildRPNFormula(ACell: PCell;
 var
   formula: PsFormula;
 begin
-  if (ACell = nil) or (not HasFormula(ACell)) then begin
-    SetLength(Result, 0);
+  Result := nil;
+  if (ACell = nil) or (not HasFormula(ACell)) then
     exit;
-  end;
+
   formula := FFormulas.FindFormula(ACell^.Row, ACell^.Col);
-  if formula = nil then begin
-    SetLength(Result, 0);
+  if formula = nil then
     exit;
-  end;
 
   if ADestCell <> nil then begin
     formula^.Parser.PrepareCopyMode(ACell, ADestCell);
@@ -3630,7 +3628,7 @@ function TsWorksheet.GetSelection: TsCellRangeArray;
 var
   i: Integer;
 begin
-  SetLength(Result, Length(FSelection));
+  SetLength(Result{%H-}, Length(FSelection));
   for i:=0 to High(FSelection) do
     Result[i] := FSelection[i];
 end;
@@ -6398,7 +6396,7 @@ var
   fmtIDs: TsSpreadformatIDArray;
   i, j: Integer;
 begin
-  SetLength(AFormatIDs, 0);
+  AFormatIDs := nil;
   if AStream = nil then
     exit;
 
@@ -7314,7 +7312,7 @@ var
 begin
   Result := false;
   AWorksheet := nil;
-  SetLength(ARanges, 0);
+  ARanges := nil;
 
   if AText = '' then
     exit;
diff --git a/components/fpspreadsheet/source/common/fpspreadsheet_clipbrd.inc b/components/fpspreadsheet/source/common/fpspreadsheet_clipbrd.inc
index e83a5eec7..798ebf278 100644
--- a/components/fpspreadsheet/source/common/fpspreadsheet_clipbrd.inc
+++ b/components/fpspreadsheet/source/common/fpspreadsheet_clipbrd.inc
@@ -76,7 +76,7 @@ var
   clipbook: TsWorkbook;
   clipsheet: TsWorksheet;
   sel: TsCellRange;
-  selArray: TsCellRangeArray;
+  selArray: TsCellRangeArray = nil;
   r, c: LongInt;
   dr, dc: LongInt;
   srcCell, destCell: PCell;
diff --git a/components/fpspreadsheet/source/common/fpsreaderwriter.pas b/components/fpspreadsheet/source/common/fpsreaderwriter.pas
index bd01b87db..e7c9c87af 100644
--- a/components/fpspreadsheet/source/common/fpsreaderwriter.pas
+++ b/components/fpspreadsheet/source/common/fpsreaderwriter.pas
@@ -1171,7 +1171,7 @@ begin
       end;
     end;
 
-  SetLength(Result, FList.Count);
+  SetLength(Result{%H-}, FList.Count);
   n := 0;
   for i := 0 to FList.Count-1 do
   begin
@@ -1205,7 +1205,7 @@ begin
       FList.Exchange(0, idx);
   end;
 
-  SetLength(Result, FList.Count);
+  SetLength(Result{%H-}, FList.Count);
   n := 0;
   for i := 0 to FList.Count - 1 do
   begin
diff --git a/components/fpspreadsheet/source/common/fpsrpn.pas b/components/fpspreadsheet/source/common/fpsrpn.pas
index a5da39096..e9d020737 100644
--- a/components/fpspreadsheet/source/common/fpsrpn.pas
+++ b/components/fpspreadsheet/source/common/fpsrpn.pas
@@ -472,7 +472,7 @@ begin
   end;
 
   // Set array length of TsRPNFormula result
-  SetLength(Result, n);
+  SetLength(Result{%H-}, n);
 
   // Copy FormulaElements to result and free temporary RPNItems
   item := AItem;
diff --git a/components/fpspreadsheet/source/common/fpsutils.pas b/components/fpspreadsheet/source/common/fpsutils.pas
index 59d9e04ee..8e2cf60c0 100644
--- a/components/fpspreadsheet/source/common/fpsutils.pas
+++ b/components/fpspreadsheet/source/common/fpsutils.pas
@@ -491,7 +491,6 @@ var
   p: Integer;
   s: String;
   f: TsRelFlags;
-  singleCell: Boolean = false;
 begin
   Result := True;
 
@@ -499,7 +498,6 @@ begin
   p := pos(':', AStr);
   if p = 0 then //exit(false);
   begin
-    singleCell := true;
     Result := ParseCellString(AStr, AFirstcellRow, AFirstCellCol, f);
     if not Result then exit;
     ALastCellRow := AFirstCellRow;
@@ -2355,7 +2353,7 @@ function RandomString(ALen: Integer): String;
 var
   i: Integer;
 begin
-  SetLength(Result, ALen);
+  SetLength(Result{%H-}, ALen);
   for i:=1 to ALen do
     Result[i] := char(Random(26) + ord('a'));
 end;
@@ -2411,6 +2409,7 @@ var
   arr1, arr2: TStringArray;
   i: Integer;
 begin
+  ARichText := nil;
   p := pos(SEPARATOR, AValue);
   if p = 0 then begin
     AText := AValue;
@@ -2438,6 +2437,7 @@ var
   L: TStringList;
   i: Integer;
 begin
+  Result := nil;
   L := TStringList.Create;
   try
     L.Delimiter := ADelimiter;
diff --git a/components/fpspreadsheet/source/common/uvirtuallayer.pas b/components/fpspreadsheet/source/common/uvirtuallayer.pas
index a57412008..756cef21e 100644
--- a/components/fpspreadsheet/source/common/uvirtuallayer.pas
+++ b/components/fpspreadsheet/source/common/uvirtuallayer.pas
@@ -113,7 +113,7 @@ procedure TVirtualLayer.SplitPath(const APath: UTF8String;const ASplittedPath: T
 var
   j,k: integer;
   LB: integer;
-  Chunk: UTF8String;
+  Chunk: UTF8String = '';
   ChunkC: integer;
 begin
   ASplittedPath.Clear;
diff --git a/components/fpspreadsheet/source/common/xlsbiff2.pas b/components/fpspreadsheet/source/common/xlsbiff2.pas
index 12bbfe37a..c2e980385 100644
--- a/components/fpspreadsheet/source/common/xlsbiff2.pas
+++ b/components/fpspreadsheet/source/common/xlsbiff2.pas
@@ -559,7 +559,7 @@ var
   lHeight: Word;
   lOptions: Word;
   Len: Byte;
-  lFontName: UTF8String;
+  lFontName: UTF8String = '';
   isDefaultFont: Boolean;
 begin
   FFont := TsFont.Create;
@@ -613,7 +613,7 @@ end;*)
 procedure TsSpreadBIFF2Reader.ReadFormat(AStream: TStream);
 var
   len: byte;
-  fmtString: AnsiString;
+  fmtString: AnsiString = '';
   nfs: String;
 begin
   // number format string
@@ -798,7 +798,7 @@ var
   L: Byte;
   ARow, ACol: Cardinal;
   XF: Word;
-  ansiStr: ansistring;
+  ansiStr: ansistring = '';
   valueStr: UTF8String;
   cell: PCell;
   sheet: TsWorksheet;
@@ -1099,7 +1099,7 @@ end;
 procedure TsSpreadBIFF2Reader.ReadStringRecord(AStream: TStream);
 var
   len: Byte;
-  s: ansistring;
+  s: ansistring = '';
 begin
   // The string is a byte-string with 8 bit length
   len := AStream.ReadByte;
@@ -1948,7 +1948,7 @@ var
   len: Integer;
   s: string; //ansistring;
   rec: TNumFormatRecord;
-  buf: array of byte;
+  buf: array of byte = nil;
 begin
   Unused(AFormatIndex);
 
@@ -2239,7 +2239,7 @@ var
   L: Byte;
   AnsiText: ansistring;
   rec: TBIFF2_LabelRecord;
-  buf: array of byte;
+  buf: array of byte = nil;
 var
   xf: Word;
 begin
diff --git a/components/fpspreadsheet/source/common/xlsbiff5.pas b/components/fpspreadsheet/source/common/xlsbiff5.pas
index 4818c0c2a..bb097e86f 100644
--- a/components/fpspreadsheet/source/common/xlsbiff5.pas
+++ b/components/fpspreadsheet/source/common/xlsbiff5.pas
@@ -397,7 +397,7 @@ end;
 procedure TsSpreadBIFF5Reader.ReadBOUNDSHEET(AStream: TStream);
 var
   len: Byte;
-  s: AnsiString;
+  s: AnsiString = '';
   sheetState: Byte;
   sheet: TsWorksheet;
   //sheetData: TsSheetData;
@@ -433,7 +433,7 @@ var
   options: Word;
   len: byte;
   formulaSize: Word;
-  ansistr: ansiString;
+  ansistr: ansiString = '';
   defName: String;
   rpnformula: TsRPNFormula;
   {%H-}extsheetIndex: Integer;
@@ -721,10 +721,10 @@ var
   B: Byte;
   ARow, ACol: Cardinal;
   XF: Word;
-  ansistr: ansistring;
+  ansistr: ansistring = '';
   valueStr: UTF8String;
   cell: PCell;
-  rtfRuns: TBiff5_RichTextFormattingRuns;
+  rtfRuns: TBiff5_RichTextFormattingRuns = nil;
   fntIndex: Integer;
   fnt: TsFont;
   sheet: TsWorksheet;
@@ -796,7 +796,7 @@ end;
 procedure TsSpreadBIFF5Reader.ReadStringRecord(AStream: TStream);
 var
   len: Word;
-  s: ansistring;
+  s: ansistring = '';
 begin
   // The string is a byte-string with 16 bit length
   len := WordLEToN(AStream.ReadWord);
@@ -1045,7 +1045,7 @@ var
   lWeight: Word;
   lEsc: Word;
   Len: Byte;
-  fontname: ansistring;
+  fontname: ansistring = '';
   font: TsFont;
   isDefaultFont: Boolean;
 begin
@@ -1132,7 +1132,7 @@ procedure TsSpreadBIFF5Reader.ReadFormat(AStream: TStream);
 var
   len: byte;
   fmtIndex: Integer;
-  fmtString: AnsiString;
+  fmtString: AnsiString = '';
   nfs: String;
 begin
   // Record FORMAT, BIFF 8 (5.49):
@@ -1162,7 +1162,7 @@ var
   ARow, ACol: Cardinal;
   XF: WORD;
   cell: PCell;
-  ansistr: ansistring;
+  ansistr: ansistring = '';
   valuestr: String;
 begin
   rec.Row := 0;  // to silence the compiler...
@@ -1223,7 +1223,7 @@ end;
 procedure TsSpreadBIFF5Writer.InternalWriteToStream(AStream: TStream);
 var
   CurrentPos: Int64;
-  sheetPos: array of Int64;
+  sheetPos: array of Int64 = nil;
   i: Integer;
   pane: Byte;
   book: TsWorkbook;
@@ -1769,7 +1769,7 @@ var
   //fmtStr: String;
   ansiFmtStr: ansiString;
   rec: TNumFormatRecord;
-  buf: array of byte;
+  buf: array of byte = nil;
 begin
   //fmtStr := NumFormatList.FormatStringForWriting(AListIndex);
   ansiFmtStr := ConvertEncoding(ANumFormatStr, encodingUTF8, FCodePage);
@@ -1867,9 +1867,9 @@ var
   L: Word;
   AnsiValue: ansistring;
   rec: TBIFF5_LabelRecord;
-  buf: array of byte;
   i, nRuns: Integer;
-  rtfRuns: TBIFF5_RichTextFormattingRuns;
+  rtfRuns: TBIFF5_RichTextFormattingRuns = nil;
+  buf: array of byte = nil;
 begin
   if (ARow >= FLimitations.MaxRowCount) or (ACol >= FLimitations.MaxColCount) then
     exit;
diff --git a/components/fpspreadsheet/source/common/xlsbiff8.pas b/components/fpspreadsheet/source/common/xlsbiff8.pas
index 8ffcb5381..39a2c02f8 100644
--- a/components/fpspreadsheet/source/common/xlsbiff8.pas
+++ b/components/fpspreadsheet/source/common/xlsbiff8.pas
@@ -967,13 +967,14 @@ function TsSpreadBIFF8Reader.ReadUnformattedWideString(const AStream: TStream;
   const ALength: WORD): WideString;
 var
   flags: Byte;
-  DecomprStrValue: WideString;
+  DecomprStrValue: WideString = '';
   i: Integer;
   len: SizeInt;
   recType: Word;
   {%H-}recSize: Word;
   C: WideChar;
 begin
+  Result := '';
   flags := AStream.ReadByte;
   dec(PendingRecordSize);
   if flags and 1 = 1 Then begin
@@ -1019,8 +1020,8 @@ function TsSpreadBIFF8Reader.ReadWideString(const AStream: TStream;
   const ALength: WORD; out ARichTextParams: TsRichTextParams): WideString;
 var
   StringFlags: BYTE;
-  DecomprStrValue: WideString;
-  AnsiStrValue: ansistring;
+  DecomprStrValue: WideString = '';
+  AnsiStrValue: ansistring = '';
   RunsCounter: WORD;
   AsianPhoneticBytes: DWORD;
   rtf_dummy: TsRichTextParams;
@@ -1031,6 +1032,7 @@ var
   recSize: WORD;
   C: WideChar;
 begin
+  Result := '';
   StringFlags := AStream.ReadByte;
   Dec(PendingRecordSize);
   if StringFlags and 8 = 8 then begin
@@ -1698,7 +1700,7 @@ var
   XF: Word;
   wideStrValue: WideString;
   cell: PCell;
-  rtfRuns: TBiff8_RichTextFormattingRuns;
+  rtfRuns: TBiff8_RichTextFormattingRuns = nil;
   fntIndex: Integer;
   fnt: TsFont;
   book: TsWorkbook;
@@ -1859,7 +1861,7 @@ var
   cell: PCell;
   ms: TMemoryStream;
   i, n: Integer;
-  rtParams: TsRichTextParams;
+  rtParams: TsRichTextParams = nil;
   fnt: TsFont;
   fntIndex: Integer;
   book: TsWorkbook;
@@ -2432,13 +2434,13 @@ var
   row, col, row1, col1, row2, col2: word;
   guid: TGUID;
   flags: DWord;
-  widestr: widestring;
+  widestr: widestring = '';
   len: DWord;
   link: String;
   linkDos: String;
   mark: String;
   dirUpCount: Word;
-  ansistr: ansistring;
+  ansistr: ansistring = '';
   size: DWord;
 begin
   { Row and column index range of cells using the hyperlink }
@@ -2574,7 +2576,7 @@ end;
 procedure TsSpreadBIFF8Reader.ReadHyperlinkToolTip(const AStream: TStream);
 var
   txt: String;
-  widestr: widestring;
+  widestr: widestring = '';
   //row, col,
   row1, col1, row2, col2: Word;
   hyperlink: PsHyperlink;
@@ -2770,7 +2772,7 @@ const
   isBIFF8 = true;
 var
   currentPos: Int64;
-  sheetPos: array of Int64;
+  sheetPos: array of Int64 = nil;
   i: Integer;
   pane: Byte;
   book: TsWorkbook;
@@ -3503,7 +3505,7 @@ var
   len: Integer;
   ws: widestring;
   rec: TNumFormatRecord;
-  buf: array of byte;
+  buf: array of byte = nil;
 begin
   ws := UTF8Decode(ANumFormatStr);
   len := Length(ws);
@@ -3819,9 +3821,9 @@ var
   WideStr: WideString;
   rec: TBIFF8_LabelRecord;
   recSST: TBIFF8_LabelSSTRecord;
-  buf: array of byte;
+  buf: array of byte = nil;
   i, nRuns, idx: Integer;
-  rtfRuns: TBiff8_RichTextFormattingRuns;
+  rtfRuns: TBiff8_RichTextFormattingRuns = nil;
 begin
   if (ARow >= FLimitations.MaxRowCount) or (ACol >= FLimitations.MaxColCount) then
     exit;
@@ -4742,7 +4744,7 @@ procedure TsSpreadBIFF8Writer.WriteTXO(AStream: TStream; AComment: PsComment);
 var
   recTXO: TBIFF8TXORecord;
   comment: widestring;
-  compressed: ansistring;
+  compressed: ansistring = '';
   len: Integer;
   wchar: widechar;
   i: Integer;
diff --git a/components/fpspreadsheet/source/common/xlscommon.pas b/components/fpspreadsheet/source/common/xlscommon.pas
index f3ea7779e..e04600f42 100644
--- a/components/fpspreadsheet/source/common/xlscommon.pas
+++ b/components/fpspreadsheet/source/common/xlscommon.pas
@@ -1102,7 +1102,7 @@ var
   i, n: Integer;
   elem: TsFormulaElement;
 begin
-  SetLength(Result, 0);
+  Result := nil;
   for i:=0 to Length(FFormula)-1 do begin
     n := Length(Result);
     elem := FFormula[i];
@@ -1740,7 +1740,7 @@ var
   rec: TBIFF25NoteRecord;
   r, c: Cardinal;
   n: Word;
-  s: ansiString;
+  s: ansiString = '';
   List: TStringList;
   sheet: TsWorksheet;
 begin
@@ -1885,7 +1885,7 @@ procedure TsSpreadBIFFReader.ReadEXTERNSHEET(AStream: TStream;
   AWorksheet: TsBasicWorksheet);
 var
   len, b: Byte;
-  ansistr: AnsiString;
+  ansistr: AnsiString = '';
   s: String;
   sheetlist: TsBIFFExternSheetList;
 begin
@@ -2046,7 +2046,7 @@ end;
 procedure TsSpreadBIFFReader.ReadHeaderFooter(AStream: TStream;
   AIsHeader: Boolean);
 var
-  s: ansistring;
+  s: ansistring = '';
   len: Byte;
 begin
   if RecordSize = 0 then
@@ -2094,7 +2094,7 @@ begin
   n := WordLEToN(AStream.ReadWord);
 
   for i := 1 to n do begin
-    AStream.ReadBuffer(rec, SizeOf(rec));
+    AStream.ReadBuffer(rec{%H-}, SizeOf(rec));
     r := WordLEToN(rec.RowIndex);
     TsWorksheet(AWorksheet).AddPageBreakToRow(r);
   end;
@@ -2790,6 +2790,7 @@ begin
     dr2 := SmallInt(r2 and $3FFF)
   else
     dr2 := SmallInt($C000 or (r2 and $3FFF));
+  ARowOffset2 := dr2;
 
   // 1 byte for col1 and col2, each
   dc1 := ShortInt(AStream.ReadByte);
@@ -3341,7 +3342,7 @@ var
   {%H-}rngIndex: Word;
   actRow, actCol: Word;
   n, i: Integer;
-  sel: TsCellRangeArray;
+  sel: TsCellRangeArray = nil;
 begin
   // Pane index
   paneIdx := AStream.ReadByte;
@@ -3441,7 +3442,7 @@ end;
 function TsSpreadBIFFReader.ReadString_8bitLen(AStream: TStream): String;
 var
   len: Byte;
-  s: ansistring;
+  s: ansistring = '';
 begin
   len := AStream.ReadByte;
   SetLength(s, len);
@@ -3493,7 +3494,7 @@ begin
   n := WordLEToN(AStream.ReadWord);
 
   for i := 1 to n do begin
-    AStream.ReadBuffer(rec, SizeOf(rec));
+    AStream.ReadBuffer(rec{%H-}, SizeOf(rec));
     c := WordLEToN(rec.ColIndex);
     TsWorksheet(AWorksheet).AddPageBreakToCol(c);
   end;
diff --git a/components/fpspreadsheet/source/common/xlsxml.pas b/components/fpspreadsheet/source/common/xlsxml.pas
index 2f95ef7d8..a40d9fe81 100644
--- a/components/fpspreadsheet/source/common/xlsxml.pas
+++ b/components/fpspreadsheet/source/common/xlsxml.pas
@@ -341,8 +341,6 @@ begin
 end;
 
 function TryStrToCFCellBorder(s: String; out ABorder: TsCellBorder): Boolean;
-var
-  cb: TsCellBorder;
 begin
   Result := true;
   if s = 'border-left' then
@@ -860,8 +858,8 @@ begin
   // initialize parameters
   condition := -1;
   range := fpsUtils.Range(Cardinal(-1), Cardinal(-1), Cardinal(-1), Cardinal(-1));
-  VarClear(op1);
-  VarClear(op2);
+  VarClear(op1{%H-});
+  VarClear(op2{%H-});
   bgColor := scNotDefined;
   fgColor := scNotDefined;
   fill := fsNoFill;
@@ -1044,7 +1042,7 @@ begin
     exit;
   end;
 
-  if condition = Cardinal(-1) then
+  if condition = -1 then
   begin
     book.AddErrorMsg('No condition given in conditional format.');
     exit;
@@ -1392,7 +1390,6 @@ procedure TsSpreadExcelXMLReader.ReadPageBreak(ANode: TDOMNode;
   AWorksheet: TsBasicWorksheet);
 var
   sheet: TsWorksheet absolute AWorksheet;
-  node: TDOMNode;
   nodeName: String;
   s: String;
   n: Integer;
@@ -1422,8 +1419,6 @@ var
   sheet: TsWorksheet absolute AWorksheet;
   nodeName: String;
   node: TDOMNode;
-  child: TDOMNode;
-  s: String;
 begin
   while ANode <> nil do
   begin
@@ -1524,7 +1519,6 @@ var
   nodeName: String;
   s: String;
   n: Integer;
-  x: Double;
 begin
   while ANode <> nil do begin
     nodeName := ANode.NodeName;
@@ -2012,6 +2006,8 @@ procedure TsSpreadExcelXMLReader.ReadFromStream(AStream: TStream;
 var
   doc: TXMLDocument;
 begin
+  Unused(APassword, AParams);
+
   try
     ReadXMLStream(doc, AStream);
 
@@ -2614,12 +2610,10 @@ procedure TsSpreadExcelXMLWriter.WriteConditionalFormatting(AStream: TStream;
   AWorksheet: TsBasicWorksheet);
 var
   book: TsWorkbook;
-  sheet: TsWorksheet;
   cf: TsConditionalFormat;
   i: Integer;
 begin
   book := TsWorkbook(FWorkbook);
-  sheet := TsWorksheet(AWorksheet);
   for i := 0 to book.GetNumConditionalFormats-1 do
   begin
     cf := book.GetConditionalFormat(i);
@@ -2731,6 +2725,9 @@ var
   xmlnsStr: String;
   dataTagStr: String;
 begin
+  Unused(ARow);
+  Unused(ACol);
+
   if ACell^.ContentType <> cctFormula then
     raise Exception.Create('WriteFormula called for calculated cell.');
 
@@ -2873,9 +2870,9 @@ begin
     if (RepeatedCols.FirstIndex <> UNASSIGNED_ROW_COL_INDEX) and
        (RepeatedCols.LastIndex <> UNASSIGNED_ROW_COL_INDEX)
     then begin
-      s := 'C' + IntToStr(RepeatedCols.FirstIndex + 1);
+      s := 'C' + {%H-}IntToStr(RepeatedCols.FirstIndex + 1);
       if RepeatedCols.FirstIndex <> RepeatedCols.LastIndex then
-        s := s + ':C' + IntToStr(RepeatedCols.LastIndex + 1);
+        s := s + ':C' + {%H-}IntToStr(RepeatedCols.LastIndex + 1);
       s := sheet.Name + '!' + s;
       print_titles_str := s;
     end;
@@ -2884,9 +2881,9 @@ begin
     if (RepeatedRows.FirstIndex <> UNASSIGNED_ROW_COL_INDEX) and
        (RepeatedRows.LastIndex <> UNASSIGNED_ROW_COL_INDEX)
     then begin
-      s := 'R' + IntToStr(RepeatedRows.FirstIndex + 1);
+      s := 'R' + {%H-}IntToStr(RepeatedRows.FirstIndex + 1);
       if RepeatedRows.FirstIndex <> RepeatedRows.LastIndex then
-        s := s + ':R' + IntToStr(RepeatedRows.LastIndex + 1);
+        s := s + ':R' + {%H-}IntToStr(RepeatedRows.LastIndex + 1);
       s := sheet.Name + '!' + s;
       if print_titles_str = '' then
         print_titles_str := s
diff --git a/components/fpspreadsheet/source/common/xlsxooxml.pas b/components/fpspreadsheet/source/common/xlsxooxml.pas
index 89c3107de..89910ecc7 100644
--- a/components/fpspreadsheet/source/common/xlsxooxml.pas
+++ b/components/fpspreadsheet/source/common/xlsxooxml.pas
@@ -59,7 +59,6 @@ type
     FBorderList: TFPList;
     FHyperlinkList: TFPList;
     FSharedFormulaBaseList: TFPList;
-    FDxfList: TFPList;
     FPalette: TsPalette;
     FThemeColors: array of TsColor;
     FLastRow, FLastCol: Cardinal;
@@ -167,9 +166,9 @@ type
     procedure WriteConditionalFormatCellRule(AStream: TStream; ARule: TsCFCellRule;
       ARange: TsCellRange; APriority: Integer);
     procedure WriteConditionalFormatColorRangeRule(AStream: TStream; ARule: TsCFColorRangeRule;
-      const ARange: TsCellRange; APriority: Integer);
+      APriority: Integer);
     procedure WriteConditionalFormatDataBarRule(AStream: TStream; ARule: TsCFDatabarRule;
-      const ARange: TsCellRange; APriority: Integer);
+      APriority: Integer);
     procedure WriteConditionalFormatRule(AStream: TStream; ARule: TsCFRule;
       const ARange: TsCellRange; var APriority: Integer);
     procedure WriteConditionalFormats(AStream: TStream; AWorksheet: TsBasicWorksheet);
@@ -1271,7 +1270,7 @@ end;
 procedure TsSpreadOOXMLReader.ReadCFAverage(ANode: TDOMNode;
   AWorksheet: TsBasicWorksheet; ARange: TsCellRange; AFormatIndex: Integer);
 var
-  s, sStdDev, sEquAve, sAboveAve: String;
+  sStdDev, sEquAve, sAboveAve: String;
   condition: TsCFCondition;
   stdDev: Double;
   sheet: TsWorksheet;
@@ -1310,8 +1309,8 @@ procedure TsSpreadOOXMLReader.ReadCFCellFormat(ANode: TDOMNode;
   AWorksheet: TsBasicWorksheet; ARange: TsCellRange; AFormatIndex: Integer);
 var
   nodeName: String;
-  s, sType, sOp: String;
-  sFormula: Array of String;
+  sOp: String;
+  sFormula: Array of String = nil;
   cf: TsCFCondition;
   found: Boolean;
   i: Integer;
@@ -1319,7 +1318,7 @@ var
   x: Double;
   r, c: Cardinal;
   condition: TsCFCondition;
-  values: array of Variant;
+  values: array of Variant = nil;
   sheet: TsWorksheet;
 begin
   sheet := TsWorksheet(AWorksheet);
@@ -2015,7 +2014,6 @@ var
   nodeName: String;
   childNode: TDOMNode;
   pattNode: TDOMNode;
-  s: String;
   fontStyles: TsFontStyles;
   fontColor: TsColor;
   bgColor: TsColor;
@@ -2854,7 +2852,7 @@ var
   nodename: String;
   totaltxt, sval: String;
   fntIndex: Integer;
-  rtParams: TsRichTextParams;
+  rtParams: TsRichTextParams = nil;
   ms: TMemoryStream;
   fnt: TsFont;
 begin
@@ -3787,10 +3785,9 @@ end;
 procedure TsSpreadOOXMLWriter.ListAllDifferentialFormats;
 var
   book: TsWorkbook;
-  sheet: TsWorksheet;
   n: Integer;
   idx: Integer;
-  i, j, k, r, d: Integer;
+  j, k, d: Integer;
   CF: TsConditionalFormat;
   rule: TsCFCellRule;
 begin
@@ -4157,7 +4154,7 @@ begin
 end;
 
 procedure TsSpreadOOXMLWriter.WriteConditionalFormatColorRangeRule(AStream: TStream;
-  ARule: TsCFColorRangeRule; const ARange: TsCellRange; APriority: Integer);
+  ARule: TsCFColorRangeRule; APriority: Integer);
 { example:
     <cfRule type="colorScale" priority="3">
       <colorScale>
@@ -4189,7 +4186,7 @@ begin
 end;
 
 procedure TsSpreadOOXMLWriter.WriteConditionalFormatDatabarRule(AStream: TStream;
-  ARule: TsCFDataBarRule; const ARange: TsCellRange; APriority: Integer);
+  ARule: TsCFDataBarRule; APriority: Integer);
 { example from test file:
       <cfRule type="dataBar" priority="1">
         <dataBar>
@@ -4225,10 +4222,10 @@ begin
     WriteConditionalFormatCellRule(AStream, TsCFCellRule(ARule), ARange, APriority)
   else
   if ARule is TsCFColorRangeRule then
-    WriteConditionalFormatColorRangeRule(AStream, TsCFColorRangeRule(ARule), ARange, APriority)
+    WriteConditionalFormatColorRangeRule(AStream, TsCFColorRangeRule(ARule), APriority)
   else
   if ARule is TsCFDataBarRule then
-    WriteConditionalFormatDataBarRule(AStream, TsCFDataBarRule(ARule), ARange, APriority)
+    WriteConditionalFormatDataBarRule(AStream, TsCFDataBarRule(ARule), APriority)
   else
     exit;
   dec(APriority);
@@ -6135,7 +6132,6 @@ procedure TsSpreadOOXMLWriter.WriteDifferentialFormat(AStream: TStream;
 
 var
   pt, bc, fc, diag: string;
-  font: TsFont;
 begin
   AppendToStream(AStream,
     '<dxf>');