(defun quoted-printable-decode-string (string &optional coding-system)
"Decode the quoted-printable encoded STRING and return the result.
-If CODING-SYSTEM is non-nil, decode the region with coding-system."
- (with-temp-buffer
+If CODING-SYSTEM is non-nil, decode the region with coding-system.
+Use of CODING-SYSTEM is deprecated; this function should deal with
+raw bytes, and coding conversion should be done separately."
+ (mm-with-unibyte-buffer
(insert string)
(quoted-printable-decode-region (point-min) (point-max) coding-system)
(buffer-string)))