constant error in active_resource/base

I am using activeresource 2.3.3

I was using ActiveResource today and it seemed to be choking on
namespaced xml, like this:
<media:group>

on line 1057 it erred with "Wrong constant name Media:group"

first i tried on line 1048
name = name.to_s.gsub(':','/')

which started failing in the same place but with: "Wrong constant name
Media::Group"

so I added this on line 1048:
name = name.to_s.gsub(':','_')

which got everything working again, but this seems a little fragile to
me. Monkey patching a gem isn't exactly the most ideal solution. Does
anyone have a recommendation as to how to properly fix this? How am I
"doing it wrong" as they say.