dumpfile locked (windows)

Is there any way to get SoapUI to unlock a dump file after it is created?

I've set up a TestCase for a REST request that responds with as a raw .pdf. I've set the Dump File property and can see the resulting file in the file system. However, after the file is created, it is remains locked by SoapUI. This causes problems trying to open the file. If I run the test again, the older file will become unlocked but the new file is locked.