diff -urN ptlib-2.12.4.old/configure.ac ptlib-2.12.4/configure.ac
--- ptlib-2.12.4.old/configure.ac	2013-06-22 21:01:51.392606863 +0200
+++ ptlib-2.12.4/configure.ac	2013-06-22 21:02:02.991606450 +0200
@@ -448,7 +448,7 @@
    ],
    [
       AC_MSG_RESULT(no)
-      PTLIB_CXXFLAGS="$PTLIB_CFLAGS -frtti"
+      PTLIB_CXXFLAGS="$PTLIB_CXXFLAGS -frtti"
    ]
 )