diff --git a/lynx-configure-c99.patch b/lynx-configure-c99.patch
new file mode 100644
index 0000000..906121e
--- /dev/null
+++ b/lynx-configure-c99.patch
@@ -0,0 +1,57 @@
+The HAVE_UNISTD_H change only shows up in configure because it's a fix
+for shell code generated by an old autoconf release.
+
+Submitted upstream:
+
+  <https://lists.nongnu.org/archive/html/lynx-dev/2022-12/msg00000.html>
+
+diff --git a/aclocal.m4 b/aclocal.m4
+index 70cde243d2129cc0..bf2cbff661de2fe1 100644
+--- a/aclocal.m4
++++ b/aclocal.m4
+@@ -6435,6 +6435,7 @@ AC_CACHE_CHECK(if we can include termio.h with curses,cf_cv_termio_and_curses,[
+     CPPFLAGS="$CPPFLAGS -DHAVE_CONFIG_H -I. -I${srcdir:-.} -I${srcdir:-.}/src -I${srcdir:-.}/WWW/Library/Implementation"
+     touch lynx_cfg.h
+     AC_TRY_COMPILE([
++#include <stdio.h>
+ #include <$1>
+ #include <termio.h>],
+     [putchar(0x0a)],
+@@ -6455,6 +6456,7 @@ AC_DEFUN([CF_TERMIO_AND_TERMIOS],
+ AC_MSG_CHECKING([termio.h and termios.h])
+ AC_CACHE_VAL(cf_cv_termio_and_termios,[
+     AC_TRY_COMPILE([
++#include <stdio.h>
+ #if HAVE_TERMIO_H
+ #include <termio.h>
+ #endif
+diff --git a/configure b/configure
+index 97f6d1d5646d05c5..6db52b514b3b9a3c 100755
+--- a/configure
++++ b/configure
+@@ -31122,6 +31122,7 @@ else
+ #line 31122 "configure"
+ #include "confdefs.h"
+ 
++#include <stdio.h>
+ #if HAVE_TERMIO_H
+ #include <termio.h>
+ #endif
+@@ -31629,6 +31630,9 @@ else
+ #line 31629 "configure"
+ #include "confdefs.h"
+ /* Thanks to Mike Rendell for this test.  */
++#if HAVE_UNISTD_H
++# include <unistd.h>
++#endif
+ #include <sys/types.h>
+ #define NGID 256
+ #undef MAX
+@@ -47492,6 +47496,7 @@ else
+ #line 47492 "configure"
+ #include "confdefs.h"
+ 
++#include <stdio.h>
+ #include <LYCurses.h>
+ #include <termio.h>
+ int
diff --git a/lynx.spec b/lynx.spec
index f1d3d65..055ac74 100644
--- a/lynx.spec
+++ b/lynx.spec
@@ -3,7 +3,7 @@
 Summary: A text-based Web browser
 Name: lynx
 Version: 2.9.0
-Release: %{devrel}.2%{?dist}.1
+Release: %{devrel}.2%{?dist}.2
 License: GPLv2
 Source: https://invisible-mirror.net/archives/lynx/tarballs/lynx%{version}%{devrel}.tar.bz2
 URL: https://lynx.invisible-island.net/
@@ -23,6 +23,8 @@ Patch2: lynx-CVE-2008-4690.patch
 # add presentation type for xhtml
 Patch3: lynx-2.9.0dev.10-xhtml.patch
 
+Patch4: lynx-configure-c99.patch
+
 Provides: webclient
 Provides: text-www-browser
 BuildRequires: dos2unix
@@ -55,6 +57,7 @@ exits quickly and swiftly displays web pages.
 %patch1 -p1
 %patch2 -p1
 %patch3 -p1
+%patch4 -p1
 
 %{!?_pkgdocdir: %global _pkgdocdir %{_docdir}/%{name}-%{version}}
 sed -e "s,^HELPFILE:.*,HELPFILE:file://localhost%{_pkgdocdir}/lynx_help/lynx_help_main.html,g" -i lynx.cfg
@@ -132,6 +135,9 @@ EOF
 %config(noreplace,missingok) %{_sysconfdir}/lynx-site.cfg
 
 %changelog
+* Fri Dec  2 2022 Florian Weimer <fweimer@redhat.com> - 2.9.0-dev.10.2.2
+- Port the configure script to C99
+
 * Thu Jul 21 2022 Fedora Release Engineering <releng@fedoraproject.org> - 2.9.0-dev.10.2.1
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_37_Mass_Rebuild