diff --git a/akka-remote/src/main/scala/akka/routing/RemoteRouters.scala b/akka-remote/src/main/scala/akka/routing/RemoteRouters.scala
index d7f62c4f61..fc08c222af 100644
--- a/akka-remote/src/main/scala/akka/routing/RemoteRouters.scala
+++ b/akka-remote/src/main/scala/akka/routing/RemoteRouters.scala
@@ -19,7 +19,7 @@ trait RemoteRouterConfig extends RouterConfig {
         case x                         ⇒ throw new ConfigurationException("unparseable remote node " + x)
       }
       val node = Stream.continually(nodes).flatten.iterator
-      val impl = context.system.asInstanceOf[ActorSystemImpl]
+      val impl = context.system.asInstanceOf[ActorSystemImpl] //FIXME should we rely on this cast to work here?
       Vector.empty[ActorRef] ++ (for (i ← 1 to nrOfInstances) yield {
         val name = "c" + i
         val deploy = Deploy("", ConfigFactory.empty(), None, props.routerConfig, RemoteScope(node.next))
diff --git a/akka-testkit/src/main/scala/akka/testkit/TestFSMRef.scala b/akka-testkit/src/main/scala/akka/testkit/TestFSMRef.scala
index 17c8a45ade..c37201cda5 100644
--- a/akka-testkit/src/main/scala/akka/testkit/TestFSMRef.scala
+++ b/akka-testkit/src/main/scala/akka/testkit/TestFSMRef.scala
@@ -88,12 +88,12 @@ class TestFSMRef[S, D, T <: Actor](
 object TestFSMRef {
 
   def apply[S, D, T <: Actor](factory: ⇒ T)(implicit ev: T <:< FSM[S, D], system: ActorSystem): TestFSMRef[S, D, T] = {
-    val impl = system.asInstanceOf[ActorSystemImpl]
+    val impl = system.asInstanceOf[ActorSystemImpl] //FIXME should we rely on this cast to work here?
     new TestFSMRef(impl, system.dispatcherFactory.prerequisites, Props(creator = () ⇒ factory), impl.guardian.asInstanceOf[InternalActorRef], TestActorRef.randomName)
   }
 
   def apply[S, D, T <: Actor](factory: ⇒ T, name: String)(implicit ev: T <:< FSM[S, D], system: ActorSystem): TestFSMRef[S, D, T] = {
-    val impl = system.asInstanceOf[ActorSystemImpl]
+    val impl = system.asInstanceOf[ActorSystemImpl] //FIXME should we rely on this cast to work here?
     new TestFSMRef(impl, system.dispatcherFactory.prerequisites, Props(creator = () ⇒ factory), impl.guardian.asInstanceOf[InternalActorRef], name)
   }
 }
diff --git a/akka-testkit/src/main/scala/akka/testkit/TestKit.scala b/akka-testkit/src/main/scala/akka/testkit/TestKit.scala
index 96b0cb151e..b5577fa747 100644
--- a/akka-testkit/src/main/scala/akka/testkit/TestKit.scala
+++ b/akka-testkit/src/main/scala/akka/testkit/TestKit.scala
@@ -102,7 +102,7 @@ class TestKit(_system: ActorSystem) {
    * registration as message target.
    */
   lazy val testActor: ActorRef = {
-    val impl = system.asInstanceOf[ActorSystemImpl]
+    val impl = system.asInstanceOf[ActorSystemImpl] //FIXME should we rely on this cast to work here?
     impl.systemActorOf(Props(new TestActor(queue))
       .copy(dispatcher = new CallingThreadDispatcher(system.dispatcherFactory.prerequisites)),
       "testActor" + TestKit.testActorId.incrementAndGet)