updating asp.net profiles

Is it safe to add a new field to an existing asp.net Profile?
Here is the current web.config
<profile enabled="true">
      <properties>
        <add name="FirstName" type="string"/>
        <add name="LastName" type="string"/>
        <add name="Address" type="string"/>
I need to add a new field called "Country".
Can I just add it to the web.config and have the runtime pick up the change or do I need to do something else? I can't have this break on me (especially with x-mas next week).
I'm using the AspNetSqlMembershipProvider with SqlServer for the backend.
Thanks in advance.
 
 
...