Diet Coke question

26 weeks pregnant past week and a half been drinking one Diet Coke a day (the can) is this safe? Haven't had a chance to see doctor will ask tho when I do. But according to Google aspertain is considered safe. I never drank diet drinks till this past week I only drink water and I do drink water during the day as well. I looked at all my pregnancy books and couldn't find anything on it other than it says in moderation just curious if anyone's doctors has said sum about it.