diff --git a/tests/sys/vm/soxstack/soxstack.c b/tests/sys/vm/soxstack/soxstack.c
index fe3eb1c03a2..ac7c9cf0374 100644
--- a/tests/sys/vm/soxstack/soxstack.c
+++ b/tests/sys/vm/soxstack/soxstack.c
@@ -16,7 +16,7 @@
 
 int	checkstack(void);
 
-#define	_STACK_FLAG_GROWS	KVME_FLAG_GROWS_UP | KVME_FLAG_GROWS_DOWN
+#define	_STACK_FLAG_GROWS	(KVME_FLAG_GROWS_UP | KVME_FLAG_GROWS_DOWN)
 int
 checkstack(void)
 {