Problem with draw2d and svg terminal: dots are always red crcles

I'm trying to export some plots to svg images with the svg terminal, but I
have a problem: when I plot points as dots, they are always represented as
small red circles. Here there is an example:

load(draw);
draw2d(
terminal=svg,
xrange=[-1,1],
yrange=[-1,1],
color=blue,
point_type=dot,
points_joined=true,
points([[-0.5,0],[0,0.5],[0.5,0]]));

The small red circles are clearly visible and they look pretty ugly in the
blue graph. Is this a bug in draw2d/gnuplot or am I missing some option? As
far as I've tried, none of the other terminals has this problem.

Thanks
Stefano