diff --git a/NEWS b/NEWS
index 64b5e0c..1c286d9 100644
--- a/NEWS
+++ b/NEWS
@@ -5,7 +5,7 @@ Changes between 3.0 and 4.0:
 
   * Not released yet.
 
-  * New in 3.99.4 prerelease (rev 169):
+  * New in 3.99.4 prerelease (rev 170):
     + Proper plugin support under Win32 and HP-UX.
     + Compilation fixes.
     + Minor bugs fixed.
diff --git a/configure.ac b/configure.ac
index b474d13..a5108c0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -418,11 +418,11 @@ dnl
 CFLAGS_save="${CFLAGS}"
 LDFLAGS_save="${LDFLAGS}"
 
-if test -n "${CXX}"; then
-  ac_cv_my_have_cxx=yes
-else
-  ac_cv_my_have_cxx=no
-fi
+AC_CACHE_CHECK([if \$CXX really works],
+  [ac_cv_my_have_cxx],
+  [AC_LANG_PUSH(C++)
+   AC_TRY_COMPILE([],,ac_cv_my_have_cxx=yes, ac_cv_my_have_cxx=no)
+   AC_LANG_POP(C++)])
 AM_CONDITIONAL(HAVE_CXX, test "${ac_cv_my_have_cxx}" = "yes")
 
 AC_CACHE_CHECK([if \$CC accepts -Wall],