--- ./fixincludes/mkheaders.in.orig	2007-06-29 11:02:37.000000000 +0200
+++ ./fixincludes/mkheaders.in	2007-06-29 11:04:35.000000000 +0200
@@ -62,7 +62,8 @@
   isysroot=$1
   shift
 else
-  isysroot=
+  isysroot=${prefix%/usr}
+  isysroot=${isysroot%/ROCK/tools.cross/*}
 fi
 
 # Directory in which to put host dependent programs and libraries