diff --git a/arch/um/sys-x86_64/Makefile b/arch/um/sys-x86_64/Makefile
index d609428..3d7da91 100644
--- a/arch/um/sys-x86_64/Makefile
+++ b/arch/um/sys-x86_64/Makefile
@@ -29,3 +29,5 @@
 module.c-dir = kernel
 
 CFLAGS_csum-partial.o := -Dcsum_partial=arch_csum_partial
+
+subdir- := util