Scala and the BuildCraft API

Recently I've begun writing several components of my mods in Scala rather than Java. In the past, I've managed to get everything to compile fine using Eclipse, however, when I try to use either MCP's compile script or compile everything in IntelliJ, I get the following errors:

value PowerReceiver is not a member of object buildcraft.api.power.PowerHandler
import buildcraft.api.power.PowerHandler.PowerReceiver;
       ^

not found: type PowerReceiver
public PowerReceiver getPowerReceiver(ForgeDirection side);
       ^

Now, obviously the code itself is correct, and this particular code has nothing to do with Scala, but as soon as there are Scala files in the project, this error appears.

Excluding the BuildCraft Power API isn't an option as my mod relies on it for the moment.

If anyone knows what's causing this issue or knows how to fix it, any insight would be greatly appreciated.