diff --git a/src/main/scala/li/cil/oc/common/tileentity/Rack.scala b/src/main/scala/li/cil/oc/common/tileentity/Rack.scala
index e9a16327d..e85fb88ae 100644
--- a/src/main/scala/li/cil/oc/common/tileentity/Rack.scala
+++ b/src/main/scala/li/cil/oc/common/tileentity/Rack.scala
@@ -59,36 +59,36 @@ class Rack extends traits.PowerAcceptor with traits.Hub with traits.PowerBalance
       case _ => None
     }
 
-    val oldSide = nodeMapping(slot)(connectableIndex)
+    val oldSide = nodeMapping(slot)(connectableIndex + 1)
     if (oldSide == newSide) return
 
     // Cut connection / remove sniffer node.
     val mountable = getMountable(slot)
     if (mountable != null && oldSide.isDefined) {
-      if (connectableIndex == 0) {
+      if (connectableIndex == -1) {
         val node = mountable.node
         val plug = sidedNode(toGlobal(oldSide.get))
         if (node != null && plug != null) {
           node.disconnect(plug)
         }
       }
-      else {
+      else if (connectableIndex >= 0) {
         snifferNodes(slot)(connectableIndex).remove()
       }
     }
 
-    nodeMapping(slot)(connectableIndex) = newSide
+    nodeMapping(slot)(connectableIndex + 1) = newSide
 
     // Establish connection / add sniffer node.
     if (mountable != null && newSide.isDefined) {
-      if (connectableIndex == 0) {
+      if (connectableIndex == -1) {
         val node = mountable.node
         val plug = sidedNode(toGlobal(newSide.get))
         if (node != null && plug != null) {
           node.connect(plug)
         }
       }
-      else if (connectableIndex < mountable.getConnectableCount) {
+      else if (connectableIndex >= 0 && connectableIndex < mountable.getConnectableCount) {
         val connectable = mountable.getConnectableAt(connectableIndex)
         if (connectable != null && connectable.node != null) {
           if (connectable.node.network == null) {
@@ -114,7 +114,7 @@ class Rack extends traits.PowerAcceptor with traits.Hub with traits.PowerBalance
         case _ => // Not connected to this side.
       }
       for (connectableIndex <- 0 until 3) {
-        mapping(connectableIndex) match {
+        mapping(connectableIndex + 1) match {
           case Some(side) if toGlobal(side) == plugSide =>
             val mountable = getMountable(slot)
             if (mountable != null && connectableIndex < mountable.getConnectableCount) {
diff --git a/src/main/scala/li/cil/oc/server/PacketHandler.scala b/src/main/scala/li/cil/oc/server/PacketHandler.scala
index a54ab678e..6d7deb06c 100644
--- a/src/main/scala/li/cil/oc/server/PacketHandler.scala
+++ b/src/main/scala/li/cil/oc/server/PacketHandler.scala
@@ -252,7 +252,7 @@ object PacketHandler extends CommonPacketHandler {
     entity match {
       case Some(t) => p.player match {
         case player: EntityPlayerMP if t.isUseableByPlayer(player) =>
-          t.connect(mountableIndex, nodeIndex, side)
+          t.connect(mountableIndex, nodeIndex - 1, side)
         case _ =>
       }
       case _ => // Invalid packet.