Do you include the constitution modifier to your starting HP if it’s negative?

When I was creating my Bard with a standard array, I considered making constitution my lowest.

I know that starting HP = the highest number of your class’ hit dice + CON mod (so 8 + CON for a Bard)

But I’m wondering if that formula still applies if the modifier is negative. My friend says it doesn’t, and I’ve tried looking it up, but all I get is if it affects your HP leveling up, not your staring HP