diff --git a/hdf.spec b/hdf.spec
index 132283a..1165699 100644
--- a/hdf.spec
+++ b/hdf.spec
@@ -1,6 +1,10 @@
+%if 0%{?rhel} < 7
+%{!?__global_ldflags: %global __global_ldflags -Wl,-z,relro}
+%endif
+
 Name: hdf
 Version: 4.2.13
-Release: 4%{?dist}
+Release: 5%{?dist}
 Summary: A general purpose library and file format for storing scientific data
 License: BSD
 Group: System Environment/Libraries
@@ -25,17 +29,11 @@ Patch9: hdf-ppc64le.patch
 # Use only if java is disabled
 Patch10: hdf-avoid_syntax_error_el6.patch
 
-BuildRoot: %{_tmppath}/%{name}-%{version}-%{release}-root-%(%{__id_u} -n)
 # For destdir/examplesdir patches
 BuildRequires: automake libtool
-BuildRequires: flex byacc libjpeg-devel zlib-devel
+BuildRequires: flex byacc libjpeg-devel zlib-devel %{!?el6:libaec-devel}
 BuildRequires: libtirpc-devel
-%if "%{?dist}" != ".el4"
 BuildRequires: gcc-gfortran
-%else
-BuildRequires: gcc-g77
-%endif
-
 
 %description
 HDF is a general purpose library and file format for storing scientific data.
@@ -46,18 +44,16 @@ objects, one can create and store almost any kind of scientific data
 structure, such as images, arrays of vectors, and structured and unstructured 
 grids. You can also mix and match them in HDF files according to your needs.
 
-
 %package devel
 Summary: HDF development files
 Group: Development/Libraries
 Provides: %{name}-static = %{version}-%{release}
-Requires: %{name} = %{version}-%{release}
+Requires: %{name}%{?_isa} = %{version}-%{release}
 Requires: libjpeg-devel zlib-devel
 
 %description devel
 HDF development headers and libraries.
 
-
 %prep
 %setup -q
 %patch0 -p1 -b .maxavailfiles
@@ -80,30 +76,33 @@ chmod a-x *hdf/*/*.c hdf/*/*.h
 # restore include file timestamps modified by patching
 touch -c -r ./hdf/src/hdfi.h.ppc ./hdf/src/hdfi.h
 
-
 %build
 # For destdir/examplesdir patches
 autoreconf -vif
 # avoid upstream compiler flags settings
 rm config/*linux-gnu
 # TODO: upstream fix
-export CFLAGS="$RPM_OPT_FLAGS -fPIC -I/usr/include/tirpc"
-export LDFLAGS="%__global_ldflags -ltirpc"
-export FFLAGS="$RPM_OPT_FLAGS -fPIC -ffixed-line-length-none"
+# Shared libraries disabled: libmfhdf.so is not correctly compiled
+# for missing link to libdf.so
+export CFLAGS="%{optflags} -fPIC -I%{_includedir}/tirpc"
+export LDFLAGS="%{__global_ldflags} -ltirpc"
+export FFLAGS="%{optflags} -fPIC -ffixed-line-length-none"
 %configure --disable-production --disable-java --disable-netcdf \
+ --enable-shared=no --enable-static=yes --enable-fortran %{!?el6:--with-szlib} \
  --includedir=%{_includedir}/%{name} --libdir=%{_libdir}/%{name}
+%make_build
 
-make
 # correct the timestamps based on files used to generate the header files
 touch -c -r hdf/src/hdf.inc hdf/src/hdf.f90
 touch -c -r hdf/src/dffunc.inc hdf/src/dffunc.f90
 touch -c -r mfhdf/fortran/mffunc.inc mfhdf/fortran/mffunc.f90
 # netcdf fortran include need same treatement, but they are not shipped
 
-
 %install
-make install DESTDIR=%{buildroot} INSTALL='install -p'
-rm  %{buildroot}%{_libdir}/%{name}/*.la
+%make_install
+
+rm -f %{buildroot}%{_libdir}/%{name}/*.la
+
 #Don't conflict with netcdf
 for file in ncdump ncgen; do
   mv %{buildroot}%{_bindir}/$file %{buildroot}%{_bindir}/h$file
@@ -112,20 +111,29 @@ for file in ncdump ncgen; do
 done
 
 # this is done to have the same timestamp on multiarch setups
-touch -c -r README.txt %{buildroot}/%{_includedir}/hdf/h4config.h
+touch -c -r README.txt %{buildroot}%{_includedir}/hdf/h4config.h
 
 # Remove an autoconf conditional from the API that is unused and cause
 # the API to be different on x86 and x86_64
-pushd %{buildroot}/%{_includedir}/hdf
+pushd %{buildroot}%{_includedir}/hdf
 grep -v 'H4_SIZEOF_INTP' h4config.h > h4config.h.tmp
 touch -c -r h4config.h h4config.h.tmp
 mv h4config.h.tmp h4config.h
 popd
 
-
+# ./testdhf fails on f28-i386 only with
+# --> /bin/sh: line 25: 22535 Segmentation fault      (core dumped) srcdir="." ./${tname} >> ${log} 2>&1
+#  but not by an arch-override=i386 ?!
+%if 0%{?fedora} >= 28
+%ifnarch %{ix86}
 %check
-make check
-
+make -j1 check
+%endif
+%endif
+%if 0%{?fedora} < 28
+%check
+make -j1 check
+%endif
 
 %files
 %license COPYING
@@ -139,8 +147,10 @@ make check
 %{_libdir}/%{name}/
 %{_defaultdocdir}/%{name}/examples
 
-
 %changelog
+* Sat Jan 20 2018 Antonio Trande <sagitter@fedoraproject.org> 4.2.13-5
+- Enable szlib support 
+
 * Wed Jan 17 2018 Pavel Raiskup <praiskup@redhat.com> - 4.2.13-4
 - rpc api moved from glibc to libtirpc:
   https://fedoraproject.org/wiki/Changes/SunRPCRemoval