--- a/configure.in
+++ b/configure.in
@@ -21,7 +21,7 @@
 ### along with Octave; see the file COPYING.  If not, write to the Free
 ### Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 
-AC_REVISION($Revision: 1.84 $)
+AC_REVISION($Revision: 1.85 $)
 AC_PREREQ(2.0)
 AC_INIT(src/octave.cc)
 AC_CONFIG_HEADER(config.h kpathsea/c-auto.h)
@@ -221,17 +221,20 @@
   ;;
 esac
 
+HOST_CXXFLAGS=
 case "$gxx_version" in
   2.6.*)
     case "$canonical_host_type" in
       rs6000-ibm-aix*)
-        CXXFLAGS="$CXXFLAGS -Wa,-u"
-        AC_MSG_RESULT([adding -Wa,-u to CXXFLAGS for AIX])
+        HOST_CXXFLAGS="-Wa,-u"
+        AC_MSG_RESULT([defining HOST_CXXFLAGS to be $HOST_CXXFLAGS])
       ;;
     esac
   ;;
 esac
 
+AC_SUBST(HOST_CXXFLAGS)
+
 ### See what libraries are used by the C++ compiler.  Need this for
 ### dynamic linking.