[trivial-gray-streams-devel] stream-read-sequence has no value on mixin.lisp compilation

[白い熊]

Hello:

I want to install trivial-gray-streams via asdf.

(asdf:load-system 'trivial-gray-streams)
...
WHEN: variable #1=#:STREAM-READ-SEQUENCE has no value
    [Condition of type SYSTEM::SIMPLE-UNBOUND-VARIABLE]

Restarts:
  0: [USE-VALUE] Input a value to be used instead of 
#:STREAM-READ-SEQUENCE.
  1: [STORE-VALUE] Input a new value for #:STREAM-READ-SEQUENCE.
  2: [TRY-RECOMPILING] Try recompiling mixin
  3: [RETRY] Retry compiling component ("trivial-gray-streams" "mixin").
  4: [ACCEPT] Continue, treating compiling component 
("trivial-gray-streams" "mixin") as having been successful.
  5: [*ABORT] Return to SLIME's top level.

I'm trying to decipher what the problem is, but haven't succeeded. 
What's going wrong?
--
白い熊