diff --git a/src/main/scala/li/cil/oc/client/GuiHandler.scala b/src/main/scala/li/cil/oc/client/GuiHandler.scala
index de0f9e2ac..928d6a2f9 100644
--- a/src/main/scala/li/cil/oc/client/GuiHandler.scala
+++ b/src/main/scala/li/cil/oc/client/GuiHandler.scala
@@ -40,7 +40,7 @@ object GuiHandler extends CommonGuiHandler {
             val address = stack.getTagCompound.getString(Settings.namespace + "server")
             val key = stack.getTagCompound.getString(Settings.namespace + "key")
             if (key != null && !key.isEmpty && address != null && !address.isEmpty) {
-              tileentity.Rack.list.
+              tileentity.Rack.list.keys.
                 flatMap(_.terminals).
                 find(term => term.rack.isPresent(term.number) match {
                 case Some(value) => value == address
diff --git a/src/main/scala/li/cil/oc/client/Proxy.scala b/src/main/scala/li/cil/oc/client/Proxy.scala
index 8c7923bda..dad460c32 100644
--- a/src/main/scala/li/cil/oc/client/Proxy.scala
+++ b/src/main/scala/li/cil/oc/client/Proxy.scala
@@ -11,6 +11,7 @@ import li.cil.oc.client.renderer.tileentity._
 import li.cil.oc.client.renderer.WirelessNetworkDebugRenderer
 import li.cil.oc.common.{Proxy => CommonProxy, tileentity}
 import li.cil.oc.common.component.TextBuffer
+import li.cil.oc.common.tileentity.Rack
 import li.cil.oc.{Items, OpenComputers}
 import net.minecraftforge.client.MinecraftForgeClient
 import net.minecraftforge.common.MinecraftForge
@@ -60,6 +61,7 @@ private[oc] class Proxy extends CommonProxy {
     FMLCommonHandler.instance().bus().register(HologramRenderer)
     FMLCommonHandler.instance().bus().register(ScreenRenderer)
     MinecraftForge.EVENT_BUS.register(WirelessNetworkDebugRenderer)
+    MinecraftForge.EVENT_BUS.register(Rack)
     MinecraftForge.EVENT_BUS.register(TextBuffer)
   }
 }
\ No newline at end of file
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 63ceb8fda..3d573f315 100644
--- a/src/main/scala/li/cil/oc/common/tileentity/Rack.scala
+++ b/src/main/scala/li/cil/oc/common/tileentity/Rack.scala
@@ -3,6 +3,7 @@ package li.cil.oc.common.tileentity
 import com.google.common.base.Strings
 import cpw.mods.fml.common.Optional
 import cpw.mods.fml.common.Optional.Method
+import cpw.mods.fml.common.eventhandler.SubscribeEvent
 import cpw.mods.fml.relauncher.{Side, SideOnly}
 import li.cil.oc.api.Network
 import li.cil.oc.api.network.{Analyzable, Connector, Visibility, Node}
@@ -20,6 +21,7 @@ import net.minecraftforge.common.util.Constants.NBT
 import net.minecraftforge.common.util.ForgeDirection
 import stargatetech2.api.bus.IBusDevice
 import scala.collection.mutable
+import net.minecraftforge.event.world.WorldEvent
 
 // See AbstractBusAware as to why we have to define the IBusDevice here.
 @Optional.Interface(iface = "stargatetech2.api.bus.IBusDevice", modid = "StargateTech2")
@@ -232,7 +234,7 @@ class Rack extends traits.PowerAcceptor with traits.Hub with traits.PowerBalance
 
   override protected def initialize() {
     super.initialize()
-    Rack.list += this
+    Rack.list += this -> Unit
   }
 
   override protected def dispose() {
@@ -387,5 +389,12 @@ class Rack extends traits.PowerAcceptor with traits.Hub with traits.PowerBalance
 }
 
 object Rack {
-  val list = mutable.Set.empty[Rack]
+  val list = mutable.WeakHashMap.empty[Rack, Unit]
+
+  @SubscribeEvent
+  def onWorldUnload(e: WorldEvent.Unload) {
+    if (e.world.isRemote) {
+      list.clear()
+    }
+  }
 }