MySQL ReadOnly user cannot see slow query log

I have the MySQL slow query log t开发者_StackOverflowurned on. For my main user account I can run this query and see results:

select * from mysql.slow_log limit 1;

I also have a "readonly" user account. This account has SELECT permission for every schema. When I log in as this user and run the above query, I get 0 results. No error or warning appears, it just looks like the log is empty.

Do I need to give my "readonly" user another permission or something? Any ideas?