diff --git a/mysys/my_uuid.c b/mysys/my_uuid.c
index d1e8331aaa1..f115806b4e9 100644
--- a/mysys/my_uuid.c
+++ b/mysys/my_uuid.c
@@ -108,7 +108,7 @@ void my_uuid_init(ulong seed1, ulong seed2)
     */
     /* purecov: begin inspected */
     my_rnd_init(&uuid_rand, (ulong) (seed2+ now/2), (ulong) (now+rand()));
-    for (i=0; i < sizeof(mac); i++)
+    for (i=0; i < array_elements(uuid_suffix) -2 ; i++)
       mac[i]= (uchar)(my_rnd(&uuid_rand)*255);
     /* purecov: end */
   }