In srfi-152.sld, the definitions of

    string->utf16be
    string-utf16le
    utf16be->string
    utf16le->string

aren't right.  The first two ignore their one argument, and none
of the four accept the optional arguments specified by SRFI 152.

The chibi-test.scm file contains three incorrect tests:

(test "substring" "cde" (substring "abcde" 2))

(test "string-replicate" "cdefab"
       (string-replicate "abcdef" 2))
(test "string-replicate" "efabcd"
       (string-replicate "abcdef" -2))

As specified by SRFI 152, substring takes exactly three arguments,
and string-replicate requires at least three arguments.

Will