diff --git a/src/editfns.c b/src/editfns.c
index a3676892444..e02cf14b968 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -1364,8 +1364,8 @@ to unibyte for insertion (see `string-make-unibyte').
 
 When operating on binary data, it may be necessary to preserve the
 original bytes of a unibyte string when inserting it into a multibyte
-buffer; to accomplish this, apply `string-as-multibyte' to the string
-and insert the result.
+buffer; to accomplish this, apply `decode-coding-string' with the
+`no-conversion' coding system to the string and insert the result.
 
 usage: (insert &rest ARGS)  */)
   (ptrdiff_t nargs, Lisp_Object *args)