--- a/configure.ac
+++ b/configure.ac
@@ -844,7 +844,12 @@
     AC_MSG_ERROR([internal configure error for the platform triplet, please file a bug report])
   fi
 fi 
-PLATDIR=plat-$MACHDEP
+
+if test x$PLATFORM_TRIPLET = x; then
+  PLATDIR=plat-$MACHDEP
+else
+  PLATDIR=plat-$PLATFORM_TRIPLET
+fi
 AC_SUBST(PLATDIR)
 AC_SUBST(PLATFORM_TRIPLET)