diff --git a/linux-2.4-xen-sparse/mkbuildtree b/linux-2.4-xen-sparse/mkbuildtree
index 40381c8895..45e8b0362d 100755
--- a/linux-2.4-xen-sparse/mkbuildtree
+++ b/linux-2.4-xen-sparse/mkbuildtree
@@ -102,9 +102,9 @@ for i in `find . -type l`; do rm -f $i; done
 relative_lndir ${RS}
 rm -f mkbuildtree
 
-set ${RS}/../linux-2.6-xen-sparse
-[ "$1" == "${RS}/../linux-2.6-xen-sparse" ] && { echo "no Linux 2.6 sparse tree at ${RS}/../linux-2.6-xen-sparse"; exit 1; }
-LINUX_26="$1"
+LINUX_26=${RS}/../linux-2.6-xen-sparse
+[ -d $LINUX_26 ] || { echo "no Linux 2.6 sparse tree at ${RS}/../linux-2.6-xen-sparse"; exit 1; }
+
 
 # Create links to the shared definitions of the Xen interfaces.
 rm -rf ${AD}/include/asm-xen/xen-public