I would like to visualize a phylogenetic tree with circles at the tips. The tips should have white fill, but a black border. How do I do this in ggtree?

Here is a MWE:

library(ape)

library(ggtree) tree <- rtree(50)

ggtree(tree) + geom_tippoint(size=3, fill="white", color="black")

ggtree(tree) + geom_point(size=3, fill="white", color="black")

With both the geom_tippoint and geom_point functions, the circles are solidly black despite the presence of fill="white". What am I doing wrong?