diff --git a/flex-2.6.4-glibc-2.26.patch b/flex-2.6.4-glibc-2.26.patch
new file mode 100644
index 0000000..895374c
--- /dev/null
+++ b/flex-2.6.4-glibc-2.26.patch
@@ -0,0 +1,14 @@
+diff -Nru flex-2.6.4.orig/configure.ac flex-2.6.4/configure.ac
+--- flex-2.6.4.orig/configure.ac	2017-10-16 23:01:23.000000000 +0200
++++ flex-2.6.4/configure.ac	2017-11-28 14:35:03.664347578 +0100
+@@ -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])
diff --git a/flex.spec b/flex.spec
index dd92c82..ddcbb66 100644
--- a/flex.spec
+++ b/flex.spec
@@ -1,7 +1,7 @@
 Name:          flex
 Epoch:         1
 Version:       2.6.4
-Release:       2mamba
+Release:       3mamba
 Summary:       A tool for creating scanners (loxical pattern recognizers)
 Group:         Development/Tools
 Vendor:        openmamba
@@ -10,6 +10,7 @@ Packager:      Silvan Calarco <silvan.calarco@mambasoft.it>
 URL:           http://flex.sourceforge.net/
 Source:        https://github.com/westes/flex.git/v%{version}/flex-%{version}.tar.bz2
 Patch0:        flex-2.6.0-gcc-5.3.0-c-comment.patch
+Patch1:        flex-2.6.4-glibc-2.26.patch
 License:       BSD
 ## AUTOBUILDREQ-BEGIN
 BuildRequires: glibc-devel
@@ -45,8 +46,6 @@ This package contains shared libraries for %{name}.
 Group:         Development/Libraries
 Summary:       Development files for %{name}
 Requires:      libfl = %{?epoch:%epoch:}%{version}-%{release}
-## note: you can add this requirement if .pc files are provided by this package
-#Requires:      pkg-config
 
 %description -n libfl-devel
 This package contains libraries and header files for developing applications that use %{name}.
@@ -54,6 +53,7 @@ This package contains libraries and header files for developing applications tha
 %prep
 %setup -q
 #%patch0 -p1
+%patch1 -p1
 
 %build
 ./autogen.sh
@@ -110,6 +110,9 @@ exit 0
 #%doc COPYING NEWS README* TODO THANKS
 
 %changelog
+* Tue Nov 28 2017 Silvan Calarco <silvan.calarco@mambasoft.it> 2.6.4-3mamba
+- patched to fix segfault with glibc 2.26
+
 * Wed Oct 18 2017 Davide Madrisan <davide.madrisan@gmail.com> 2.6.4-2mamba
 - rebuild for removing the linker dependency to libc.so.6(GLIBC_2.26)