diff --git a/unit/atf-src/atf-c/detail/sanity.h b/unit/atf-src/atf-c/detail/sanity.h
index 0b4f3e4756..161c6f0af7 100644
--- a/unit/atf-src/atf-c/detail/sanity.h
+++ b/unit/atf-src/atf-c/detail/sanity.h
@@ -56,14 +56,17 @@ void atf_sanity_post(const char *, int, const char *);
 
 #define INV(x) \
     do { \
+	(void)(x); \
     } while (0)
 
 #define PRE(x) \
     do { \
+	(void)(x); \
     } while (0)
 
 #define POST(x) \
     do { \
+	(void)(x); \
     } while (0)
 
 #endif /* !defined(NDEBUG) */