Let $X$, $Y$ be a smooth projective varieties, say over the complex numbers, both acted upon by a connected linear group $G$. Let $f\colon X\to Y$ be an equivariant rational map. Let $Z$ be a smooth $G$-subvariety sitting in the indeterminacy locus of $f$.
Let $X'$ be the blowup of $Z$ in $X$.
Wish a reference to show (1) the action of $G$ extends to $X'$, and (2) the  rational
map $f\colon X'\to Y$ induced by $f$ is equivariant.