--- gcc-4.7.2/libstdc++-v3/configure.host.orig	2013-02-14 22:54:13.919299554 +0100
+++ gcc-4.7.2/libstdc++-v3/configure.host	2013-02-14 22:55:31.551121397 +0100
@@ -276,6 +276,10 @@
     esac
     OPT_LDFLAGS="${OPT_LDFLAGS} \$(lt_host_flags)"
     ;;
+  mingw64*)
+    os_include_dir="os/mingw32-w64"
+    error_constants_dir="os/mingw32-w64"
+    ;;
   netbsd*)
     os_include_dir="os/bsd/netbsd"
     ;;