Hello, The vector output stream implementation is missing an applicable method for STREAM-LINE-COLUMN, which is required for character output support. Patch follows. Ariel diff -rN -u old-babel/src/streams.lisp new-babel/src/streams.lisp --- old-babel/src/streams.lisp 2009-11-29 11:31:24.000000000 +0200 +++ new-babel/src/streams.lisp 2009-11-29 11:31:25.000000000 +0200 @@ -323,6 +323,11 @@ (extend-vector-output-stream-buffer sequence stream :start start :end end))) sequence) +(defmethod stream-line-column ((stream vector-output-stream)) + "Dummy line-column method that always returns NIL, needed for +character output streams." + nil) + (defmethod stream-file-position ((stream vector-stream)) "Simply returns the index into the underlying vector." (declare (optimize speed))