System.Security.SecurityException in CRM Plugin

I recently got the following error when trying to call the Bing Maps rest endpoint in a CRM 2011 plug-in. Since I wasn’t able to reproduce this in my test code, I did a search, and found out that calls to HttpUtility are not allowed in the sandbox environment for plug-ins for CRM Online.
I had the following piece of code:

HttpUtility.UrlEncode(...)

I changed it to:

Uri.EscapeUriString(...)

This resolved the issue, and now I am geocoding with no problems.