How do you specify a custom return code?

Playing with the Powershell Deployment Toolkit for the first time, and have an issue with the first application I’m trying. A simple setup.exe that runs silently, no switches required. The install runs successfully per the event viewer, but I get this from the toolkit - Execution failed with exit code [1]. At this point, I’m just testing the script locally, so SCCM isn’t involved.

Exit-Script -ExitCode 70000
Results in script exiting with exit code 70000.