Rectangular hygrometer holder to round corners

I store filament in the vacuum type bags. I wanted to start putting hygrometers in some of these bags with the filament, but I didn't want the poky edges of the rectangular hygrometer to harm the bag. I also didn't want to use the round hygrometers that go inside the spool because that's where the desiccant goes and I want to make sure the hygrometer is reading the humidity the filament sees.