[1.8] RandomPositionGenerator crashes Minecraft

[ChaKha]

I've been working on some custom AI for my custom mob (flying penguin), but I've currently run into a snag. I'm trying to set it like so:

public boolean shouldExecute() {
	if (theEntityCreature.worldObj.getClosestPlayerToEntity(theEntityCreature, 3.0D) == null) {
		return false;
	}
	Vec3 vec3 = RandomPositionGenerator.findRandomTarget((EntityCreature) theEntityCreature, 30, 10);//ERROR
        if (vec3 == null) {
            return false;
        } else {
            randPosX = vec3.xCoord;
            randPosY = vec3.yCoord;
            randPosZ = vec3.zCoord;
            return true;
        }
}

It crashes when it reaches the RandomPositonGenerator. What's wrong with it?

[ChaKha]

Somehow I missed it in the console, but apparently its a class cast exception. I need a way to cast though. RandomPositionGenerator wants an EntityCreature, but I can't seem to cast from EntityPenguinMob (custom entity). How could I get around the cast?