diff --git a/ide/exttooleditdlg.pas b/ide/exttooleditdlg.pas
index 6d0fefdb73..b57f1476cd 100644
--- a/ide/exttooleditdlg.pas
+++ b/ide/exttooleditdlg.pas
@@ -904,7 +904,7 @@ begin
   else
     s:='$'+fTransferMacros[i].Name+'()';
   ALine := MemoParameters.CaretPos.Y;
-  If MemoParameters.Lines.Count = 0 Then
+  if ALine >= MemoParameters.Lines.Count then
     MemoParameters.Lines.Add('');
   AStr := MemoParameters.Lines[Aline];
   MemoParameters.Lines[Aline] := AStr + s;
diff --git a/lcl/interfaces/qt/qtprivate.pp b/lcl/interfaces/qt/qtprivate.pp
index 9747321cce..7f7d20fdef 100644
--- a/lcl/interfaces/qt/qtprivate.pp
+++ b/lcl/interfaces/qt/qtprivate.pp
@@ -428,12 +428,13 @@ begin
 
   // simplified because of issue #29670
   // allow insert invalid index like others do
-  if Index >= FStringlist.Count then
+  if Index >= FStringList.Count then
     Index := FStringList.Add(S)
   else
     FStringList.Insert(Index, S);
   W := GetUTF8String(S);
   TQtTextEdit(FOwner.Handle).insertLine(Index, W);
+  FTextChanged := False; // FStringList is already updated, no need to update from WS.
 end;
 
 procedure TQtMemoStrings.LoadFromFile(const FileName: string);