Error with IStream.Seek() - ole

Question

I have a very old piece of code to handle Excel files in Delphi 5, which I adapted to work with Delphi 2005, which I used professionally until 2010. Since then, there was no reasonable free version of Delphi. Therefore, it is only now that using Delphi 10.2.3 Tokyo I would like to adapt it once again.
A problem that I was not able to solve is related to the use of OleStream.Seek(...) in the function given below, where I get a fatal error with all expressions in OleCheck(...).
Also, I didn't find any hint on a similar problem searching for the function OleStream.Seek(...) on the Internet.
The code is the following
function Streamseek(offset : longint; origin: word):string;
var
Pos : longInt ; // Pos: largeint;
begin
if FBIFFVersion > biff4 then begin
case Origin of
soFromBeginning:
OleCheck(OStream.Seek(Offset,STREAM_SEEK_SET,Pos)); // ENUM: set =0
soFromCurrent:
OleCheck(OStream.Seek(Offset,STREAM_SEEK_CUR,Pos)); /// 1 cur
soFromEnd:
OleCheck(OStream.Seek(Offset,STREAM_SEEK_END,Pos)); // 2 end
end;
Of course, it is just one function in a much bigger program, which is not relevant here.
My problem is: I searched for
OStream.Seek(Offset,STREAM_SEEK_SET,Pos) on the Internet, but I could only find OleStream.seek(offset : longint; origin: word):string; except for one webpage, but there the same types were used.
Working with IStream in Delphi
So, I wonder what parameter types need to be used.
In the German version of Delphi 10.2.3, I get the error:
[dcc32 Fehler] line(878): E2033 Die Typen der tatsächlichen und formalen Var-Parameter müssen übereinstimmen
In English:
The types of the real and the formal var parameters must be the same.
It is clear that largeint is not a modern parameter type, and I only see the possibility that, instead of Integer, LongInt, Int64 or else is needed since the number of parameters should be OK.
LongInt instead of Integer for offset does not work, Longint instead of LargeInt does not work for pos.
Has anyone an idea what might be the reason for the error? What are the required types of this function in Delphi 10.2.3?