Error in for loop - bad result

program bad;

var
    arr: array[0..1, 0..4] of byte;
    tmpByte: byte;

begin
    for tmpByte := 0 to 4 do begin
        arr[0, tmpByte] := tmpByte;
    end;

    Writeln (arr[0,0]);
    Writeln (arr[0,1]);
    Writeln (arr[0,2]);
    Writeln (arr[0,3]);
    Writeln (arr[0,4]);
end.