diff --git a/extlib/benz/include/picrin/compat.h b/extlib/benz/include/picrin/compat.h
index ff7268c3..e6abc5dd 100644
--- a/extlib/benz/include/picrin/compat.h
+++ b/extlib/benz/include/picrin/compat.h
@@ -89,7 +89,7 @@ extern "C" {
 
 #else
 
-# define assert(v) 0
+# define assert(v) (void)0
 
 PIC_INLINE int
 isspace(int c)