diff --git a/src/ce_common.pas b/src/ce_common.pas
index 314eb730..e8162f3c 100644
--- a/src/ce_common.pas
+++ b/src/ce_common.pas
@@ -27,6 +27,8 @@ type
 
   TIntByString = class(specialize TFPGMap<string, integer>);
 
+  TIndentationMode = (imSpaces, imTabs);
+
   TCECompiler = (dmd, gdc, ldc);
 
   // aliased to get a custom prop inspector
@@ -258,6 +260,16 @@ type
    *)
   function globToReg(const glob: string ): string;
 
+  (**
+   * Detects the main indetation mode used in a file
+   *)
+  function indentationMode(strings: TStrings): TIndentationMode;
+
+    (**
+   * Detects the main indetation mode used in a file
+   *)
+  function indentationMode(const fname: string): TIndentationMode;
+
 var
   // supplementatl directories to find background tools
   additionalPath: string;
@@ -1155,6 +1167,41 @@ begin
   end;
 end;
 
+function indentationMode(strings: TStrings): TIndentationMode;
+var
+  i: integer;
+  s: string;
+  tabs: integer = 0;
+  spcs: integer = 0;
+begin
+  for s in strings do
+    for i := 1 to s.length do
+    begin
+      case s[i] of
+        #9: tabs += 1;
+        ' ': spcs += 1;
+        else break;
+      end;
+    end;
+  if spcs >= tabs then
+    result := imSpaces
+  else
+    result := imTabs;
+end;
+
+function indentationMode(const fname: string): TIndentationMode;
+var
+  str: TStringList;
+begin
+  str := TStringList.Create;
+  try
+    str.LoadFromFile(fname);
+    result := indentationMode(str);
+  finally
+    str.Free;
+  end;
+end;
+
 initialization
   registerClasses([TCEPersistentShortcut]);
 end.
diff --git a/src/ce_editoroptions.pas b/src/ce_editoroptions.pas
index 5d622d38..98e51cad 100644
--- a/src/ce_editoroptions.pas
+++ b/src/ce_editoroptions.pas
@@ -31,6 +31,7 @@ type
     //
     fShortCuts: TCollection;
     //
+    fDetectIndentationMode: boolean;
     fCurrLineAttribs: TSynSelectedColor;
     fSelAttribs: TSynSelectedColor;
     fFoldedColor: TSynSelectedColor;
@@ -85,6 +86,7 @@ type
     property completionMenuWidth: integer read fCompletionMenuWidth write fCompletionMenuWidth;
     property currentLine: TSynSelectedColor read fCurrLineAttribs write setCurrLineAttribs;
     property ddocDelay: Integer read fDDocDelay write setDDocDelay;
+    property detectIndentMode: boolean read fDetectIndentationMode write fDetectIndentationMode;
     property folding: TSynSelectedColor read fFoldedColor write setFoldedColor;
     property font: TFont read fFont write setFont;
     property highlighterDlang: TPersistent read fD2Syn write setD2Syn;
@@ -281,6 +283,7 @@ begin
     background := srcopt.background;
     lineNumberEvery := srcopt.lineNumberEvery;
     identifierMatchOptions:=srcopt.identifierMatchOptions;
+    detectIndentMode:=srcopt.detectIndentMode;
 
     tabulationWidth := srcopt.tabulationWidth;
     blockIndentation := srcopt.blockIndentation;
@@ -462,6 +465,7 @@ end;
 
 procedure TCEEditorOptions.docFocused(aDoc: TCESynMemo);
 begin
+  Assign();
 end;
 
 procedure TCEEditorOptions.docChanged(aDoc: TCESynMemo);
@@ -632,6 +636,7 @@ begin
   anEditor.RightEdge := rightEdge;
   anEditor.RightEdgeColor := rightEdgeColor;
   anEditor.IdentifierMatchOptions:= identifierMatchOptions;
+  anEditor.detectIndentMode := detectIndentMode;
   for i := 0 to anEditor.Keystrokes.Count-1 do
   begin
     kst := anEditor.Keystrokes.Items[i];
diff --git a/src/ce_synmemo.pas b/src/ce_synmemo.pas
index d289ab5e..832d90ab 100644
--- a/src/ce_synmemo.pas
+++ b/src/ce_synmemo.pas
@@ -143,6 +143,7 @@ type
     fAutoCloseCurlyBrace: TBraceAutoCloseStyle;
     fLexToks: TLexTokenList;
     fDisableFileDateCheck: boolean;
+    fDetectIndentMode: boolean;
     procedure setMatchOpts(value: TIdentifierMatchOptions);
     function getMouseFileBytePos: Integer;
     procedure changeNotify(Sender: TObject);
@@ -219,6 +220,7 @@ type
     property isTemporary: boolean read getIfTemp;
     property TextView;
     //
+    property detectIndentMode: boolean read fDetectIndentMode write fDetectIndentMode;
     property disableFileDateCheck: boolean read fDisableFileDateCheck write fDisableFileDateCheck;
     property MouseStart: Integer read getMouseFileBytePos;
     property D2Highlighter: TSynD2Syn read fD2Highlighter;
@@ -1387,6 +1389,14 @@ begin
     loadCache;
     fCacheLoaded := true;
   end;
+  //
+  if detectIndentMode then
+  begin
+    case indentationMode(lines) of
+      imTabs: Options:= Options - [eoTabsToSpaces];
+      imSpaces: Options:= Options + [eoTabsToSpaces];
+    end;
+  end;
   subjDocChanged(TCEMultiDocSubject(fMultiDocSubject), self);
 end;