XML DataSource not correctly escaping ampersands

I'm using an XML DataSource referencing the Response property of a SOAP Request. The raw XML of the Response has elements containing correctly escaped ampersands. When I configure the DataSource to use the content of those Response elements using XPath, the resulting requests I've configured in a DataSource Loop contain un-escaped ampersands. This generates a SOAP fault for the looped request, obviously.

Example initial response XML:

 
<courseSectionList>
     <courseSectionIdType>
          <subject>THTR&amp;FLM</subject>
     </courseSectionIdType>
</courseSectionList>

DataSource Row XPath:

//courseSectionList/courseSectionIdType

DataSource Column XPath:

subject

Looped Request Body Definition:

<subject>${DataSource#subject}</subject>

Actual Request from HTTP log:

<subject>THTR&FLM</subject>