diff --git a/lib/defines.h b/lib/defines.h
index d3416f11..5ef11c02 100644
--- a/lib/defines.h
+++ b/lib/defines.h
@@ -169,6 +169,7 @@ static inline void memzero(void *ptr, size_t size)
 #define SCALE DAY
 #endif
 
+#define WIDTHOF(x)   (sizeof(x) * CHAR_BIT)
 #define NITEMS(arr)  (sizeof((arr)) / sizeof((arr)[0]))
 
 /* Copy string pointed by B to array A with size checking.  It was originally