System.Web-->client profile, can I change to full framework?

I am attempting to utilize the System.Web assembly in some code to help me write out a query string.
I am able to reference using System.Web without issue, but when I attempt to access System.Web.HttpUtility, I get an error saying it’s not recognized.
Digging into it a little deeper, it looks like this is caused because the software is probably distributed with the client profile of this assembly rather than the full framework version.

Is there a way to get around this issue, or am I stuck finding another method to approach this problem?