configure.ac |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/configure.ac b/configure.ac
index ad2f1e6..4f9d7be 100644
--- a/configure.ac
+++ b/configure.ac
@@ -8,6 +8,7 @@ AC_PROG_CXX
 
 # set CFLAGS and CXXFLAGS
 user_CFLAGS=${CFLAGS}
+user_CXXFLAGS=${CXXFLAGS}
 generic_CFLAGS="-Wall"
 ext_CFLAGS=""
 case "${host_cpu}-${host_os}" in
@@ -37,7 +38,7 @@ AC_ARG_ENABLE(shortread,    [  --enable-shortreads     use shortread mode],
 AC_ARG_ENABLE(intel64,      [  --enable-intel64        optimize for Intel64 CPU such as Xeon and Core2],
 			  [ext_CFLAGS="${ext_CFLAGS} -mtune=nocona"], [])
 CFLAGS="${generic_CFLAGS} ${ext_CFLAGS} ${user_CFLAGS}"
-CXXFLAGS=$CFLAGS
+CXXFLAGS="${generic_CFLAGS} ${ext_CFLAGS} ${user_CXXFLAGS}"
 
 AC_STDC_HEADERS
 AC_CHECK_HEADER(zlib.h)