diff --git a/lib/defines.h b/lib/defines.h
index b2185793..1a25e580 100644
--- a/lib/defines.h
+++ b/lib/defines.h
@@ -171,6 +171,8 @@ static inline void memzero(void *ptr, size_t size)
 #define SCALE DAY
 #endif
 
+#define NITEMS(arr)  (sizeof((arr)) / sizeof((arr)[0]))
+
 /* Copy string pointed by B to array A with size checking.  It was originally
    in lmain.c but is _very_ useful elsewhere.  Some setuid root programs with
    very sloppy coding used to assume that BUFSIZ will always be enough...  */