diff --git a/package/flex/0001-flex-disable-documentation.patch b/package/flex/0001-flex-disable-documentation.patch
index 68bec128ee..b017b41385 100644
--- a/package/flex/0001-flex-disable-documentation.patch
+++ b/package/flex/0001-flex-disable-documentation.patch
@@ -1,4 +1,7 @@
-flex: disable documentation
+From a98443c6a72d5821d4e0152311e5c3eb4cdff25c Mon Sep 17 00:00:00 2001
+From: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
+Date: Wed, 13 Sep 2017 17:26:48 +0300
+Subject: [PATCH] flex: disable documentation
 
 Since we prevent the flex binary to be built, we also need to prevent
 the documentation to be built, otherwise it will fail like this:
@@ -9,11 +12,17 @@ make[2]: *** No rule to make target '../src/flex', needed by 'flex.1'.
 Stop.
 
 Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
+[Adrian: patch Makefile.am instead of Makefile.in]
+Signed-off-by: Adrian Perez de Castro <aperez@igalia.com>
+---
+ Makefile.am | 1 -
+ 1 file changed, 1 deletion(-)
 
-diff -rup a/Makefile.in b/Makefile.in
---- a/Makefile.in	2017-05-06 15:49:09.000000000 +0100
-+++ b/Makefile.in	2017-05-10 14:35:20.152794902 +0100
-@@ -450,7 +450,6 @@ EXTRA_DIST = \
+diff --git a/Makefile.am b/Makefile.am
+index 638c549..9db3420 100644
+--- a/Makefile.am
++++ b/Makefile.am
+@@ -43,7 +43,6 @@ EXTRA_DIST = \
  
  SUBDIRS = \
  	src \
@@ -21,3 +30,6 @@ diff -rup a/Makefile.in b/Makefile.in
  	examples \
  	po \
  	tests \
+-- 
+2.14.1
+
diff --git a/package/flex/0002-build-AC_USE_SYSTEM_EXTENSIONS-in-configure.ac.patch b/package/flex/0002-build-AC_USE_SYSTEM_EXTENSIONS-in-configure.ac.patch
new file mode 100644
index 0000000000..06747a36e1
--- /dev/null
+++ b/package/flex/0002-build-AC_USE_SYSTEM_EXTENSIONS-in-configure.ac.patch
@@ -0,0 +1,35 @@
+From ffa886a580929f26fd5e5a40c9c5334955c48553 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.
+
+Backported from: 24fd0551333e7eded87b64dd36062da3df2f6380
+Signed-off-by: Adrian Perez de Castro <aperez@igalia.com>
+---
+ configure.ac | 2 ++
+ 1 file changed, 2 insertions(+)
+
+diff --git a/configure.ac b/configure.ac
+index 55e774b..c879fe1 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])
+-- 
+2.14.1
+
diff --git a/package/flex/flex.mk b/package/flex/flex.mk
index 0196624e9a..aeac4ada87 100644
--- a/package/flex/flex.mk
+++ b/package/flex/flex.mk
@@ -10,8 +10,14 @@ FLEX_INSTALL_STAGING = YES
 FLEX_LICENSE = FLEX
 FLEX_LICENSE_FILES = COPYING
 FLEX_DEPENDENCIES = $(TARGET_NLS_DEPENDENCIES) host-m4
+
+# 0001-flex-disable-documentation.patch
+# 0002-build-AC_USE_SYSTEM_EXTENSIONS-in-configure.ac.patch
+FLEX_AUTORECONF = YES
+FLEX_GETTEXTIZE = YES
 FLEX_CONF_ENV = ac_cv_path_M4=/usr/bin/m4 \
 	ac_cv_func_reallocarray=no
+
 HOST_FLEX_DEPENDENCIES = host-m4
 
 define FLEX_DISABLE_PROGRAM