Using libfat in a project The following assumes that you are using one of the example NDS templates. The first step is adding libfat to the list of libraries. In the ARM9 Makefile (or the top level one if there is no specific ARM9 Makefile), look for the list of libraries. It should look like: LIBS := -lnds9 Change this to: LIBS := -lfat -lnds9 The order is important! Make sure that -lfat comes before -lnds9. The include directory will already be set, so you don't need to worry about this.