diff --git a/ide/cleandirdlg.lfm b/ide/cleandirdlg.lfm
index af02f4991a..9340a387e7 100644
--- a/ide/cleandirdlg.lfm
+++ b/ide/cleandirdlg.lfm
@@ -155,12 +155,9 @@ object CleanDirectoryDialog: TCleanDirectoryDialog
     OKButton.Name = 'OKButton'
     OKButton.Caption = '&ОК'
     HelpButton.Name = 'HelpButton'
-    HelpButton.Caption = '&Справка'
     CloseButton.Name = 'CloseButton'
-    CloseButton.Caption = '&Закрыть'
     CloseButton.Enabled = False
     CancelButton.Name = 'CancelButton'
-    CancelButton.Caption = 'Отмена'
     TabOrder = 3
     ShowButtons = [pbOK, pbCancel, pbHelp]
     ShowBevel = False
diff --git a/ide/cleandirdlg.pas b/ide/cleandirdlg.pas
index fd030cd322..209d66f752 100644
--- a/ide/cleandirdlg.pas
+++ b/ide/cleandirdlg.pas
@@ -100,6 +100,7 @@ procedure TCleanDirectoryDialog.OkButtonClick(Sender: TObject);
 var
   List: TStrings;
 begin
+  ModalResult:=mrNone;
   SaveSettings;
   if not SearchFilesToDelete(List) then exit;
   try
@@ -325,6 +326,7 @@ var
     const FilterAsText: string): boolean;
   var
     Expr: String;
+    s: String;
   begin
     Result:=false;
     if FilterAsText='' then begin
@@ -339,12 +341,16 @@ var
       Expr:=FilterAsText;
     try
       Filter.Expression:=Expr;
+      // do a simple test
+      Filter.Exec('test.file');
       Result:=true;
     except
       on E: Exception do begin
-        MessageDlg('Invalid Mask',
-          'The mask "'+FilterAsText+'" is not a valid expression.',
-          mtError,[mbCancel],0);
+        if SimpleSyntax then
+          s:=Format(lisTheFileMaskIsInvalid, [FilterAsText])
+        else
+          s:=Format(lisTheFileMaskIsNotAValidRegularExpression, [FilterAsText]);
+        MessageDlg(lisInvalidMask, s, mtError, [mbCancel], 0);
       end;
     end;
   end;
@@ -364,10 +370,10 @@ begin
     Directory:=AppendPathDelim(Directory);
 
     // setup filters
-    SetupFilter(RemoveFilterRegExpr,SimpleSyntaxRemoveCheckbox.Checked,
-      RemoveCombobox.Text);
-    SetupFilter(KeepFilterRegExpr,SimpleSyntaxKeepCheckbox.Checked,
-      KeepCombobox.Text);
+    if not SetupFilter(RemoveFilterRegExpr,SimpleSyntaxRemoveCheckbox.Checked,
+      RemoveCombobox.Text) then exit;
+    if not SetupFilter(KeepFilterRegExpr,SimpleSyntaxKeepCheckbox.Checked,
+      KeepCombobox.Text) then exit;
 
     // search files
     List:=TStringList.Create;
diff --git a/ide/ideprocs.pp b/ide/ideprocs.pp
index a6001d67c9..63da17d82e 100644
--- a/ide/ideprocs.pp
+++ b/ide/ideprocs.pp
@@ -2515,12 +2515,12 @@ end;
 {------------------------------------------------------------------------------
   function SimpleSyntaxToRegExpr(const Src: string): string;
 
-  . -> \.
   * -> .*
   ? -> .
   , -> |
   ; -> |
-  
+  Backslash characters .+
+
   Finally enclose by ^( )$
 ------------------------------------------------------------------------------}
 function SimpleSyntaxToRegExpr(const Src: string): string;
@@ -2538,7 +2538,7 @@ begin
     c:=Src[SrcPos];
     case c of
     '\': inc(SrcPos);
-    '*','.':
+    '*','.','+':
       inc(DestLen);
     end;
     inc(SrcPos);
@@ -2559,11 +2559,11 @@ begin
         Result[DestPos]:=Src[SrcPos];
         inc(DestPos);
       end;
-    '.':
+    '.','+':
       begin
         Result[DestPos]:='\';
         inc(DestPos);
-        Result[DestPos]:='.';
+        Result[DestPos]:=c;
         inc(DestPos);
       end;
     '*':
diff --git a/ide/lazarusidestrconsts.pas b/ide/lazarusidestrconsts.pas
index ad69b72219..ce62c8ed19 100644
--- a/ide/lazarusidestrconsts.pas
+++ b/ide/lazarusidestrconsts.pas
@@ -3316,6 +3316,10 @@ resourcestring
   lisUnableToReadFile = 'Unable to read file';
   lisUnableToReadFilename = 'Unable to read file %s%s%s.';
   lisErrorDeletingFile = 'Error deleting file';
+  lisInvalidMask = 'Invalid Mask';
+  lisTheFileMaskIsNotAValidRegularExpression = 'The file mask "%s" is not a '
+    +'valid regular expression.';
+  lisTheFileMaskIsInvalid = 'The file mask "%s" is invalid.';
   lisUnableToDeleteAmbiguousFile = 'Unable to delete ambiguous file %s%s%s';
   lisErrorRenamingFile = 'Error renaming file';
   lisUnableToRenameAmbiguousFileTo = 'Unable to rename ambiguous file %s%s%s%'