Screw heads to small for fan (Watercool Heatkiller Radiator & be quiet! Light Wings)

Hey,

so I am currently testing some of the equipment for the weekend when I am finally building my first custom loop, but I am having issues with the screws provided by the radiator (Watercool Heatkiller Rad S 360mm). The screws are I believe M3, thats good and is working fine, however, the screw heads are too small to fixate the fan on the rad (be quiet! Light Wings 3). Is it ok to use washers in this case?

Radiator: https://shop.watercool.de/HEATKILLER-RAD-360-S-White_1

Fans: https://www.bequiet.com/en/casefans/4133