diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 7ae8ca64..2d184450 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -4050,9 +4050,11 @@ provide all of the headers specified in C89 (as amended in 1995):
 @file{setjmp.h}, @file{signal.h}, @file{stdarg.h}, @file{stddef.h},
 @file{stdio.h}, @file{stdlib.h}, @file{string.h}, @file{time.h},
 @file{wchar.h}, and @file{wctype.h}.  Most programs can safely include
-these headers unconditionally.  All other headers, including all headers
-from later revisions of the C standard, need to be tested for
-if your program is intended to be portable to C89
+these headers unconditionally.  A program not intended to be portable to
+C89 can also safely include the C99-specified headers @file{complex.h},
+@file{fenv.h}, @file{inttypes.h}, @file{stdbool.h}, @file{stdint.h}, and
+@file{tgmath.h}.  All other headers, including all headers
+from later revisions of the C standard, likely need to be tested for
 (@pxref{Header Files}).
 
 If your program needs to be portable to a @emph{freestanding}