diff --git a/ppl.spec b/ppl.spec
index 7d2b51c..2d88f92 100644
--- a/ppl.spec
+++ b/ppl.spec
@@ -1,6 +1,6 @@
 Name:		ppl
 Version:	0.9
-Release:	10%{?dist}
+Release:	11%{?dist}
 
 Summary:	The Parma Polyhedra Library: a library of numerical abstractions
 Group:		Development/Libraries
@@ -54,7 +54,10 @@ BuildRequires:	glpk-devel >= 4.13
 This package contains the (mixed integer) linear programming solver ppl_lpsol
 and the program ppl_lcdd for vertex/facet enumeration of convex polyhedra.
 
+%ifnarch ppc64
 %package gprolog
+# The `gprolog' package is not available on ppc64:
+# the GNU Prolog interface must thus be disabled for that architecture.
 Summary:	The GNU Prolog interface of the Parma Polyhedra Library
 Group:		Development/Libraries
 BuildRequires:	gprolog >= 1.2.19
@@ -62,7 +65,9 @@ Requires:	ppl = %{version}-%{release}, ppl-pwl = %{version}-%{release}, gprolog
 %description gprolog
 This package adds GNU Prolog support to the Parma Polyhedra Library (PPL).
 Install this package if you want to use the library in GNU Prolog programs.
+%endif
 
+%ifnarch ppc64
 %package gprolog-static
 Summary:	The static archive for the GNU Prolog interface of the Parma Polyhedra Library
 Group:		Development/Libraries
@@ -70,6 +75,7 @@ Requires:	ppl-gprolog = %{version}-%{release}
 %description gprolog-static
 This package contains the static archive for the GNU Prolog interface
 of the Parma Polyhedra Library.
+%endif
 
 %package swiprolog
 Summary:	The SWI-Prolog interface of the Parma Polyhedra Library
@@ -149,7 +155,12 @@ This package contains the static archive for the Parma Watchdog Library.
 %patch2 -p1
 
 %build
-%configure --enable-shared --disable-rpath CPPFLAGS="-I%{_includedir}/glpk -I%{_libdir}/gprolog-`gprolog --version 2>&1 | head -1 | sed -e "s/.* \([^ ]*\)$/\1/g"`/include -I%{_includedir}/Yap"
+CPPFLAGS="-I%{_includedir}/glpk"
+%ifnarch ppc64
+CPPFLAGS="$CPPFLAGS -I%{_libdir}/gprolog-`gprolog --version 2>&1 | head -1 | sed -e "s/.* \([^ ]*\)$/\1/g"`/include"
+%endif
+CPPFLAGS="$CPPFLAGS -I%{_includedir}/Yap"
+%configure --enable-shared --disable-rpath CPPFLAGS="$CPPFLAGS"
 sed -i 's|^hardcode_libdir_flag_spec=.*|hardcode_libdir_flag_spec=""|g' libtool
 sed -i 's|^runpath_var=LD_RUN_PATH|runpath_var=DIE_RPATH_DIE|g' libtool
 make %{?_smp_mflags}
@@ -198,16 +209,20 @@ rm -f %{buildroot}%{_libdir}/*.la %{buildroot}%{_libdir}/%{name}/*.la
 %{_mandir}/man1/ppl_lcdd.1.gz
 %{_mandir}/man1/ppl_lpsol.1.gz
 
+%ifnarch ppc64
 %files gprolog
 %defattr(-,root,root,-)
 %doc interfaces/Prolog/GNU/README.gprolog
 %{_bindir}/ppl_gprolog
 %{_libdir}/%{name}/ppl_gprolog.pl
 %{_libdir}/%{name}/libppl_gprolog.so
+%endif
 
+%ifnarch ppc64
 %files gprolog-static
 %defattr(-,root,root,-)
 %{_libdir}/%{name}/libppl_gprolog.a
+%endif
 
 %files swiprolog
 %defattr(-,root,root,-)
@@ -262,6 +277,10 @@ rm -f %{buildroot}%{_libdir}/*.la %{buildroot}%{_libdir}/%{name}/*.la
 rm -rf %{buildroot}
 
 %changelog
+* Thu Jul 05 2007 Roberto Bagnara <bagnara@cs.unipr.it> 0.9-11
+- The `gprolog' package is not available on the ppc64 architecture:
+  so do `ppl-gprolog' and `ppl-gprolog-static'.
+
 * Tue Jul 03 2007 Roberto Bagnara <bagnara@cs.unipr.it> 0.9-10
 - Use `%%{buildroot}' consistently, instead of  `$RPM_BUILD_ROOT'.