Possible fake proof of $1= -1$

Well, I remembered this after having Algebra II a year ago, is it possible that this is a valid proof that $1 = -1$?

$$ 1 = \sqrt{1} = \sqrt{-1\cdot-1} = \sqrt{-1} \cdot \sqrt{-1} = i \cdot i = i^2 = -1 $$

$$ \therefore 1 = -1 $$

So is this actually fully valid? Or can it be disproved?

Answer

I think the problem is between $\sqrt{ -1 \dot{} -1 }$ and $\sqrt{-1} \dot{} \sqrt{-1}$.