Count if every other 5th cell is equal to 0

Hi,

As the title says, I need to count every 5th cell if the cell value = 0.

I had something something similar on another sheet:

=SUM(IF(MOD(COLUMN($M4:$FO4),3)=0,$M4:$FO4,0))

But my poor brain couldn't modify it. Any help appreciated! The cell references don't matter, I can sort those.

Cheers