diff --git a/ghc-rpm-macros.spec b/ghc-rpm-macros.spec
index 2170c0e..f098e1c 100644
--- a/ghc-rpm-macros.spec
+++ b/ghc-rpm-macros.spec
@@ -10,8 +10,8 @@
 #%%global without_hscolour 1
 
 Name:           ghc-rpm-macros
-Version:        1.6.19
-Release:        3%{?dist}
+Version:        1.6.20
+Release:        1%{?dist}
 Summary:        RPM macros for building Haskell packages for GHC
 
 License:        GPLv3+
@@ -161,6 +161,11 @@ EOF
 
 
 %changelog
+* Sun Jul 30 2017 Jens Petersen <petersen@redhat.com> - 1.6.20-1
+- add _ghclicensedir macro
+- add ghc_smp_mflags macro, since -j4 breaks reproducible-builds.org completely
+  (report by Bernhard Wiedemann)
+
 * Wed Jul 26 2017 Fedora Release Engineering <releng@fedoraproject.org> - 1.6.19-3
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_27_Mass_Rebuild
 
diff --git a/macros.ghc b/macros.ghc
index 5076832..257bcad 100644
--- a/macros.ghc
+++ b/macros.ghc
@@ -64,6 +64,8 @@ LDFLAGS="${LDFLAGS:-%{?__global_ldflags}}"; export LDFLAGS\
 # top library dir
 %ghclibdir %{_libdir}/ghc-%{ghc_version}
 
+%_ghclicensedir %{?_defaultlicensedir}%{!?_defaultlicensedir:%_docdir}
+
 # ghc_gen_filelists [name] [version]
 %ghc_gen_filelists()\
 %define pkgname %{?1}%{!?1:%{pkg_name}}\
@@ -89,7 +91,7 @@ if [ -d "%{buildroot}%{docdir}" ]; then\
 echo "%{docdir}" >> %{basepkg}-devel.files\
 fi\
 %if 0%{?1:1}\
-for i in $(ls %{buildroot}%{?_defaultlicensedir}%{!?_defaultlicensedir:%_docdir}/%{!?1:%{name}}%{?1:%{basepkg}}); do\
+for i in $(ls %{buildroot}%{_ghclicensedir}/%{!?1:%{name}}%{?1:%{basepkg}}); do\
 echo "%%license %{?1:%{pkgnamever}/}$i" >> %{basepkg}.files\
 done\
 %endif\
@@ -114,13 +116,13 @@ install -D --mode=0644 %{pkgnamever}.conf %{buildroot}%{ghclibdir}/package.conf.
 %ghc_bin_build\
 %global debug_package %{nil}\
 %cabal_configure\
-%cabal build %{?cabal_build_options}
+%cabal build %{?ghc_smp_mflags} %{?cabal_build_options}
 
 # ghc_lib_build_without_haddock [name] [version]
 %ghc_lib_build_without_haddock()\
 %global debug_package %{nil}\
-%cabal_configure %{!?without_prof:-p} %{!?ghc_without_shared:--enable-shared} %{?ghc_without_shared:--disable-shared} %{?pkg_name:--htmldir=%{ghclibdocdir}/%{pkg_name}-%{version}} %{?1:--docdir=%{?_defaultlicensedir}%{!?_defaultlicensedir:%_docdir}/ghc-%1%{!?fedora:-%2} --htmldir=%{ghclibdocdir}/%1-%2} %{?ghc_with_lib_for_ghci:--enable-library-for-ghci}\
-%cabal build  %{?cabal_build_options}\
+%cabal_configure %{!?without_prof:-p} %{!?ghc_without_shared:--enable-shared} %{?ghc_without_shared:--disable-shared} %{?pkg_name:--htmldir=%{ghclibdocdir}/%{pkg_name}-%{version}} %{?1:--docdir=%{_ghclicensedir}/ghc-%1%{!?fedora:-%2} --htmldir=%{ghclibdocdir}/%1-%2} %{?ghc_subpackaging:--user}%{!?ghc_subpackaging:--global} %{?ghc_with_lib_for_ghci:--enable-library-for-ghci}\
+%cabal build %{?ghc_smp_mflags} %{?cabal_build_options}\
 %{nil}
 
 # ghc_lib_build [name] [version]
diff --git a/macros.ghc-fedora b/macros.ghc-fedora
index 1bfd7b8..fbb087b 100644
--- a/macros.ghc-fedora
+++ b/macros.ghc-fedora
@@ -1,5 +1,5 @@
 # Fedora specific settings
 
-%_ghcdocdir %{?_defaultlicensedir}%{!?_defaultlicensedir:%_docdir}/%{name}
+%_ghcdocdir %{_ghclicensedir}/%{name}
 
 %cabal_install_options -v