If you have an unused hole from a previous antenna (or whatever) use one of FireStick's snap in hole plugs to seal it up. 

The HPA-S (small) hole plug package holds 2 plugs for 3/8" holes and 2 plugs for 1/2" holes. 

The HPA-L (large) hole plug package holds 2 plugs for 3/4" holes and 2 plugs for 7/8" holes