diff --git a/giac.changes b/giac.changes
index afcc535..0bb082a 100644
--- a/giac.changes
+++ b/giac.changes
@@ -1,3 +1,10 @@
+-------------------------------------------------------------------
+Fri Sep 25 10:57:20 UTC 2020 - Jan Engelhardt <jengelh@inai.de>
+
+- Modernize RPM constructs. Remove %post(un) logic that expands
+  to empty strings.
+- Remove pkgconfig(ao) from giac-devel, the headers do not use it.
+
 -------------------------------------------------------------------
 Sun Sep 20 09:32:35 UTC 2020 - Jan Engelhardt <jengelh@inai.de>
 
diff --git a/giac.spec b/giac.spec
index 4f2edba..3e452f4 100644
--- a/giac.spec
+++ b/giac.spec
@@ -105,7 +105,6 @@ Requires:       lib%{name}%{soname} = %{version}
 Requires:       mpfi-devel
 Requires:       mpfr-devel
 Requires:       ntl-devel
-Requires:       pkgconfig(ao)
 Requires:       pkgconfig(gsl)
 
 %description    devel
@@ -124,7 +123,7 @@ usage of giac, a computer algebra system.
 %lang_package
 
 %prep
-%setup -q -n %{name}-%{mainver}
+%autosetup -p1 -n %{name}-%{mainver}
 
 # remove all hidden files
 find . -type f -iname '.*' -delete
@@ -133,7 +132,7 @@ find . -type f -iname '.*' -delete
 %configure \
     --enable-gui \
     --enable-static=no
-make %{?_smp_mflags}
+%make_build
 
 %install
 %make_install
@@ -143,12 +142,12 @@ rm -f %{buildroot}/%{_libdir}/*.la
 rm -rf %{buildroot}%{_datadir}/application-registry
 # install man page
 find debian -type f -name \*.1 | while read i; do
-f=$(basename $i)
-install -Dm 0644 $i %{buildroot}%{_mandir}/man1/$f; done
+	install -Dm 0644 $i "%{buildroot}/%{_mandir}/man1/${i##*/}"
+done
 # install mimeinfo
 install -Dm 0644 debian/%{name}.sharedmimeinfo %{buildroot}%{_datadir}/mime/packages/%{name}.xml
 # remove makefiles from %%doc
-find %{buildroot}%{_datadir}/%{name}/doc -type f -name \*akefile* -delete
+find %{buildroot}%{_datadir}/%{name}/doc -type f -iname "Makefile*" -delete
 # remove zero-length
 find %{buildroot}%{_datadir}/%{name}/doc -type f -empty -delete
 # fix non-executable-script
@@ -173,9 +172,6 @@ rm %{buildroot}%{_docdir}/giac/Makefile.am
 %fdupes -s %{buildroot}%{_datadir}
 
 %post
-%mime_database_post
-%desktop_database_post
-%icon_theme_cache_post
 %install_info --info-dir=%{_infodir} %{_infodir}/%{name}_es.info%{ext_info}
 %install_info --info-dir=%{_infodir} %{_infodir}/%{name}_us.info%{ext_info}
 
@@ -185,11 +181,6 @@ if [ $1 -eq 0 ]; then
 %install_info_delete --info-dir=%{_infodir} %{_infodir}/%{name}_us.info%{ext_info}
 fi
 
-%postun
-%mime_database_postun
-%desktop_database_postun
-%icon_theme_cache_postun
-
 %post   -n lib%{name}%{soname} -p /sbin/ldconfig
 %postun -n lib%{name}%{soname} -p /sbin/ldconfig