diff --git a/src/main/java/li/cil/oc/api/internal/Robot.java b/src/main/java/li/cil/oc/api/internal/Robot.java
index f99b98540..ed3d5e041 100644
--- a/src/main/java/li/cil/oc/api/internal/Robot.java
+++ b/src/main/java/li/cil/oc/api/internal/Robot.java
@@ -17,8 +17,8 @@ import net.minecraftforge.fluids.IFluidHandler;
  * follows:
  * <ul>
  * <li>Tool</li>
- * <li><tt>containerCount</tt> hot-swappable components.</li>
- * <li><tt>inventorySize</tt> internal inventory slots.</li>
+ * <li><tt>equipmentInventory.getSizeInventory</tt> hot-swappable components.</li>
+ * <li><tt>mainInventory.getSizeInventory</tt> internal inventory slots.</li>
  * <li><tt>componentCount</tt> hard-wired components.</li>
  * </ul>
  * Note that there may be no hot-swappable (or even built-in) components or
@@ -28,26 +28,11 @@ import net.minecraftforge.fluids.IFluidHandler;
  * This interface is <em>not meant to be implemented</em>, just used.
  */
 public interface Robot extends Agent, Environment, EnvironmentHost, Rotatable, Tiered, ISidedInventory, IFluidHandler {
-    /**
-     * The number of hot-swappable component slots in this robot.
-     * <p/>
-     * <em>Note</em>: this will always be three, regardless of the number of
-     * installed containers. For unused slots the inventory will simply be
-     * empty at that slot.
-     */
-    int containerCount();
-
     /**
      * The number of built-in components in this robot.
      */
     int componentCount();
 
-    /**
-     * The size of the internal inventory in this robot, excluding tool and
-     * component slots.
-     */
-    int inventorySize();
-
     /**
      * Get the environment for the component in the specified slot.
      * <p/>
diff --git a/src/main/scala/li/cil/oc/common/tileentity/Robot.scala b/src/main/scala/li/cil/oc/common/tileentity/Robot.scala
index 30431731c..0f475e517 100644
--- a/src/main/scala/li/cil/oc/common/tileentity/Robot.scala
+++ b/src/main/scala/li/cil/oc/common/tileentity/Robot.scala
@@ -139,7 +139,9 @@ class Robot extends traits.Computer with traits.PowerInformation with IFluidHand
 
   override def setSelectedSlot(index: Int): Unit = {
     selectedSlot = index max 0 min mainInventory.getSizeInventory - 1
-    ServerPacketSender.sendRobotSelectedSlotChange(this)
+    if (world != null) {
+      ServerPacketSender.sendRobotSelectedSlotChange(this)
+    }
   }
 
   val tank = new internal.MultiTank {
@@ -157,7 +159,7 @@ class Robot extends traits.Computer with traits.PowerInformation with IFluidHand
 
   // Fixed number of containers (mostly due to GUI limitation, but also because
   // I find three to be a large enough number for sufficient flexibility).
-  override def containerCount = 3
+  def containerCount = 3
 
   override def componentCount = info.components.length
 
diff --git a/src/main/scala/li/cil/oc/common/tileentity/RobotProxy.scala b/src/main/scala/li/cil/oc/common/tileentity/RobotProxy.scala
index 469c0d771..e7672547c 100644
--- a/src/main/scala/li/cil/oc/common/tileentity/RobotProxy.scala
+++ b/src/main/scala/li/cil/oc/common/tileentity/RobotProxy.scala
@@ -40,10 +40,16 @@ class RobotProxy(val robot: Robot) extends traits.Computer with traits.PowerInfo
 
   override def tank = robot.tank
 
+  override def selectedSlot = robot.selectedSlot
+
   override def setSelectedSlot(index: Int) = robot.setSelectedSlot(index)
 
+  override def selectedTank = robot.selectedTank
+
   override def setSelectedTank(index: Int) = robot.setSelectedTank(index)
 
+  override def player() = robot.player()
+
   // ----------------------------------------------------------------------- //
 
   override def connectComponents() {}
@@ -56,20 +62,12 @@ class RobotProxy(val robot: Robot) extends traits.Computer with traits.PowerInfo
   @SideOnly(Side.CLIENT)
   override def setRunning(value: Boolean) = robot.setRunning(value)
 
-  override def player() = robot.player()
-
-  override def containerCount = robot.containerCount
+  // ----------------------------------------------------------------------- //
 
   override def componentCount = robot.componentCount
 
-  override def inventorySize = robot.inventorySize
-
   override def getComponentInSlot(index: Int) = robot.getComponentInSlot(index)
 
-  override def selectedSlot = robot.selectedSlot
-
-  override def selectedTank = robot.selectedTank
-
   override def synchronizeSlot(slot: Int) = robot.synchronizeSlot(slot)
 
   // ----------------------------------------------------------------------- //
diff --git a/src/main/scala/li/cil/oc/server/machine/Machine.scala b/src/main/scala/li/cil/oc/server/machine/Machine.scala
index 0adf53818..957c8fc2b 100644
--- a/src/main/scala/li/cil/oc/server/machine/Machine.scala
+++ b/src/main/scala/li/cil/oc/server/machine/Machine.scala
@@ -188,6 +188,7 @@ class Machine(val host: MachineHost) extends prefab.ManagedEnvironment with mach
 
   override def start(): Boolean = state.synchronized(state.top match {
     case Machine.State.Stopped =>
+      onHostChanged()
       processAddedComponents()
       verifyComponents()
       if (!Settings.get.ignorePower && node.globalBuffer < cost) {
diff --git a/src/main/scala/li/cil/oc/util/ExtendedArguments.scala b/src/main/scala/li/cil/oc/util/ExtendedArguments.scala
index b19e9b6f4..a6b682f6d 100644
--- a/src/main/scala/li/cil/oc/util/ExtendedArguments.scala
+++ b/src/main/scala/li/cil/oc/util/ExtendedArguments.scala
@@ -1,7 +1,6 @@
 package li.cil.oc.util
 
 import li.cil.oc.api.internal.MultiTank
-import li.cil.oc.api.internal.Robot
 import li.cil.oc.api.machine.Arguments
 import net.minecraft.inventory.IInventory
 import net.minecraftforge.common.util.ForgeDirection
@@ -38,14 +37,6 @@ object ExtendedArguments {
       else default
     }
 
-    def checkSlot(robot: Robot, n: Int) = {
-      val slot = args.checkInteger(n) - 1
-      if (slot < 0 || slot >= robot.inventorySize) {
-        throw new IllegalArgumentException("invalid slot")
-      }
-      slot + 1 + robot.containerCount
-    }
-
     def checkTank(multi: MultiTank, n: Int) = {
       val tank = args.checkInteger(n) - 1
       if (tank < 0 || tank >= multi.tankCount) {