make: $(patsubst,%,%/%.txt,$(BASE_NAMES)) not quite right

[Edd]

Hello,

I'm having a little trouble with the patsubst function of gnu make. Please 
consider:

BASE_NAMES = a b c
EXPANDED_NAMES = $(patsubst,%,%/%.txt,$(BASE_NAMES))

I was hoping EXPANDED_NAMES would expand to:
a/a.txt b/b.txt c/c.txt

but instead it expands to:
a/%.txt b/%.txt c/%.txt

Is there a way to achieve the behavior I want?

Kind regards,

Edd

--
Edd Dawson  www.nunswithguns.net  |  "It's sad when someone you know
To email me, cut the crap.        |   becomes someone you knew."
edd@nunswithcrapguns.net          |             - Henry Rollins