Accidently Buying Boosts

Unknown

So... this has happened a few times now, the last one costing me 100HP.

Add the boost, tapping to add more (max 5 stack) and only having ~3-4, it automatically pops up the screen to buy more and I accidentally tap the "buy More" button.

Perhaps there could be a confirmation or move the buy screen or not allow it to just be tapped in the exact same spot as the "add boost" button?

I guess it's my fault for going to fast, but it's pretty inconvenient.