diff --git a/lib/zebra.h b/lib/zebra.h
index f8a6be3..404b832 100644
--- a/lib/zebra.h
+++ b/lib/zebra.h
@@ -387,6 +387,8 @@
 #define MIN(a, b) ((a) < (b) ? (a) : (b))
 #endif
 
+#define ZEBRA_NUM_OF(x) (sizeof (x) / sizeof (x[0]))
+
 /* For old definition. */
 #ifndef IN6_ARE_ADDR_EQUAL
 #define IN6_ARE_ADDR_EQUAL IN6_IS_ADDR_EQUAL