Assault Squad: Crash on IS-2 reinforcement

[Colonel Casualty]

I picked up MoW: Assault Squad in the Humble Weekly Bundle, and have been playing it with a friend who just reinstalled it. Both of us are using the Steam version, unmodded and fresh installs. For some reason, we're crashing the moment either of us try to build an IS-2. I think something's wrong with the unit file.

The unit icon is wrong for some reason:


This is the crash error:


As far as I can tell, the other tanks are a-ok. Anyone got ideas for how to fix it?