Hy, I am trying to complete XLS or XLSM files. The number (double) aren't well-formed in XLSM, because decimal separator is a dot instead of comma for my system. Formulas which are using these number cells can't run. With XLS, i don't have any problem. The cell format defined with Excel is a numeric with 4 decimals. In source code of POI (i use 3.10 beta 2): XSSFCell.setCellValue(double value){ ... _cell.setV(String.valueOf(value)); ... } For example, with value=1.0015 => String.valueOf(value) = "1.0015" In any case, my source code: double value = Double.parseDouble("1.0015"); cell.setCellValue(value); //xls => OK (cell completed with : 1,0015 ) , xlsm => KO (cell completed with : 1.0015) Is there a bug? Why with XLS Files, i don't have problem? Thanks. DoD