diff --git a/test/make-iso9660-image.sh b/test/make-iso9660-image.sh
index b8fcce5ddddd..17f44e78ff01 100644
--- a/test/make-iso9660-image.sh
+++ b/test/make-iso9660-image.sh
@@ -25,7 +25,7 @@ if test -n "$init"; then
 fi
 
 # !!! -f is a quick hack.
-ensureDir $out
+ensureDir $out/iso
 mkisofs -r -J -o $out/iso/$isoName $bootFlags \
     -graft-points $graftList