diff --git a/backport-build-AC_USE_SYSTEM_EXTENSIONS-in-configure.ac.patch b/backport-build-AC_USE_SYSTEM_EXTENSIONS-in-configure.ac.patch
new file mode 100644
index 0000000000000000000000000000000000000000..3d7807d1712813a8c824995eb66ab763ce6f90eb
--- /dev/null
+++ b/backport-build-AC_USE_SYSTEM_EXTENSIONS-in-configure.ac.patch
@@ -0,0 +1,32 @@
+From 24fd0551333e7eded87b64dd36062da3df2f6380 Mon Sep 17 00:00:00 2001
+From: Explorer09 <explorer09@gmail.com>
+Date: Mon, 4 Sep 2017 10:47:33 +0800
+Subject: [PATCH] build: AC_USE_SYSTEM_EXTENSIONS in configure.ac.
+
+This would, e.g. define _GNU_SOURCE in config.h, enabling the
+reallocarray() prototype in glibc 2.26+ on Linux systems with that
+version of glibc.
+
+Fixes #241.
+---
+ configure.ac | 2 ++
+ 1 file changed, 2 insertions(+)
+
+diff --git a/configure.ac b/configure.ac
+index c6f12d6..3c977a4 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -25,8 +25,10 @@
+ # autoconf requirements and initialization
+ 
+ AC_INIT([the fast lexical analyser generator],[2.6.4],[flex-help@lists.sourceforge.net],[flex])
++AC_PREREQ([2.60])
+ AC_CONFIG_SRCDIR([src/scan.l])
+ AC_CONFIG_AUX_DIR([build-aux])
++AC_USE_SYSTEM_EXTENSIONS
+ LT_INIT
+ AM_INIT_AUTOMAKE([1.11.3 -Wno-portability foreign check-news std-options dist-lzip parallel-tests subdir-objects])
+ AC_CONFIG_HEADER([src/config.h])
+-- 
+1.8.3.1
+
diff --git a/flex-2.6.1.tar.xz b/flex-2.6.1.tar.xz
deleted file mode 100644
index fd897a909ba23c812f6b6a26352557ce904649e1..0000000000000000000000000000000000000000
Binary files a/flex-2.6.1.tar.xz and /dev/null differ
diff --git a/flex-2.6.4.tar.gz b/flex-2.6.4.tar.gz
new file mode 100644
index 0000000000000000000000000000000000000000..fd328f959c8d1f111fcb5dae9ca377f2e60c238c
Binary files /dev/null and b/flex-2.6.4.tar.gz differ
diff --git a/flex.spec b/flex.spec
index 9cf45bb7d07fd8a5a33a5bbbb5232e7597380f69..717787e8a819fc3e9b43b34e655f55bc05fc0a70 100644
--- a/flex.spec
+++ b/flex.spec
@@ -1,12 +1,14 @@
 Name: flex
-Version: 2.6.1
-Release: 13
+Version: 2.6.4
+Release: 1
 Summary: A fast lexical analyzer generator
 License: BSD and LGPLv2+
 URL: https://github.com/westes/flex
-Source0: https://github.com/westes/flex/releases/download/v%{version}/flex-%{version}.tar.xz
+Source0: https://github.com/westes/flex/releases/download/v%{version}/flex-%{version}.tar.gz
 
-BuildRequires: gcc gettext help2man m4 bison
+Patch6000: backport-build-AC_USE_SYSTEM_EXTENSIONS-in-configure.ac.patch
+
+BuildRequires: gcc gettext help2man m4 bison texinfo
 Requires: m4
 Requires(post): info
 Requires(preun): info
@@ -39,6 +41,7 @@ Man pages and other related documents for %{name}.
 %autosetup -n %{name}-%{version}
 
 %build
+autoreconf
 %configure
 %make_build
 
@@ -72,7 +75,7 @@ fi
 %dir %{_pkgdocdir}
 %license COPYING
 %{_pkgdocdir}/NEWS
-%{_pkgdocdir}/README
+%{_pkgdocdir}/README.md
 %{_bindir}/*
 %{_includedir}/FlexLexer.h
 %{_infodir}/flex.info*
@@ -87,6 +90,12 @@ fi
 %{_mandir}/man1/*
 
 %changelog
+* Mon May 11 2020 openEuler Buildteam <buildteam@openeuler.org> - 2.6.4-1
+- Type:requirement
+- ID:NA
+- SUG:NA
+- DESC:update to 2.6.4
+
 * Tue Jan 7 2020 chengquan<chengquan3@huawei.com> - 2.6.1-13
 - Type:enhancement
 - ID:NA