diff --git a/akka-stream-typed/src/test/scala/akka/stream/typed/scaladsl/ActorSourceSinkSpec.scala b/akka-stream-typed/src/test/scala/akka/stream/typed/scaladsl/ActorSourceSinkSpec.scala
index 8d5ba79249..958240326c 100644
--- a/akka-stream-typed/src/test/scala/akka/stream/typed/scaladsl/ActorSourceSinkSpec.scala
+++ b/akka-stream-typed/src/test/scala/akka/stream/typed/scaladsl/ActorSourceSinkSpec.scala
@@ -3,16 +3,16 @@
  */
 package akka.stream.typed.scaladsl
 
+import akka.actor.typed.ActorRef
+import akka.actor.typed.TypedAkkaSpecWithShutdown
 import akka.actor.typed.scaladsl.Behaviors
 import akka.stream.OverflowStrategy
-import akka.actor.typed.{ ActorRef, ActorSystem }
-import akka.testkit.TestKit
-import akka.testkit.typed.scaladsl._
-import akka.stream.scaladsl.{ Keep, Sink, Source }
+import akka.stream.scaladsl.Keep
+import akka.stream.scaladsl.Sink
+import akka.stream.scaladsl.Source
 import akka.stream.typed.ActorMaterializer
-import akka.testkit.typed.TestKitSettings
-import org.scalatest.{ BeforeAndAfterAll, Matchers, WordSpecLike }
-import org.scalatest.concurrent.ScalaFutures
+import akka.testkit.typed.TestKit
+import akka.testkit.typed.scaladsl._
 
 object ActorSourceSinkSpec {
 
@@ -23,22 +23,11 @@ object ActorSourceSinkSpec {
   case object Failed extends AckProto
 }
 
-class ActorSourceSinkSpec extends TestKit(akka.actor.ActorSystem("ActorSourceSinkSpec")) with WordSpecLike with BeforeAndAfterAll with Matchers with ScalaFutures {
+class ActorSourceSinkSpec extends TestKit with TypedAkkaSpecWithShutdown {
   import ActorSourceSinkSpec._
-  import akka.actor.typed.scaladsl.adapter._
 
-  // FIXME use Typed Teskit
-  // The materializer creates a top-level actor when materializing a stream.
-  // Currently that is not supported, because a Typed Teskit uses a typed actor system
-  // with a custom guardian. Because of custom guardian, an exception is being thrown
-  // when trying to create a top level actor during materialization.
-  implicit val sys = ActorSystem.wrap(system)
-  implicit val testkitSettings = TestKitSettings(sys)
   implicit val mat = ActorMaterializer()
 
-  override protected def afterAll(): Unit =
-    sys.terminate()
-
   "ActorSink" should {
 
     "accept messages" in {
@@ -76,7 +65,7 @@ class ActorSourceSinkSpec extends TestKit(akka.actor.ActorSystem("ActorSourceSin
           }
       }
 
-      val pilotRef: ActorRef[AckProto] = system.actorOf(PropsAdapter(autoPilot))
+      val pilotRef: ActorRef[AckProto] = spawn(autoPilot)
 
       val in =
         Source.queue[String](10, OverflowStrategy.dropBuffer)
diff --git a/akka-stream-typed/src/test/scala/akka/stream/typed/scaladsl/CustomGuardianAndMaterializerSpec.scala b/akka-stream-typed/src/test/scala/akka/stream/typed/scaladsl/CustomGuardianAndMaterializerSpec.scala
new file mode 100644
index 0000000000..2b83bfad24
--- /dev/null
+++ b/akka-stream-typed/src/test/scala/akka/stream/typed/scaladsl/CustomGuardianAndMaterializerSpec.scala
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2017 Lightbend Inc. <http://www.lightbend.com/>
+ */
+package akka.stream.typed.scaladsl
+
+import scala.concurrent.Future
+
+import akka.actor.typed.ActorRef
+import akka.actor.typed.TypedAkkaSpecWithShutdown
+import akka.actor.typed.scaladsl.Behaviors
+import akka.stream.scaladsl.Sink
+import akka.stream.scaladsl.Source
+import akka.stream.typed.ActorMaterializer
+import akka.testkit.typed.TestKit
+
+object CustomGuardianAndMaterializerSpec {
+
+  sealed trait GuardianProtocol
+  case class Init(sender: ActorRef[String]) extends GuardianProtocol
+  case class Msg(sender: ActorRef[String], msg: String) extends GuardianProtocol
+  case object Complete extends GuardianProtocol
+  case object Failed extends GuardianProtocol
+}
+
+class CustomGuardianAndMaterializerSpec extends TestKit with TypedAkkaSpecWithShutdown {
+  import CustomGuardianAndMaterializerSpec._
+
+  val guardian = Behaviors.immutable[GuardianProtocol] {
+    (_, msg) ⇒ Behaviors.same
+  }
+
+  implicit val mat = ActorMaterializer()
+
+  "ActorMaterializer" should {
+
+    "work with typed ActorSystem with custom guardian" in {
+      val it: Future[String] = Source.single("hello").runWith(Sink.head)
+
+      it.futureValue should ===("hello")
+    }
+
+  }
+
+}
diff --git a/akka-stream/src/main/scala/akka/stream/ActorMaterializer.scala b/akka-stream/src/main/scala/akka/stream/ActorMaterializer.scala
index cb9e8731c8..ef542d0372 100644
--- a/akka-stream/src/main/scala/akka/stream/ActorMaterializer.scala
+++ b/akka-stream/src/main/scala/akka/stream/ActorMaterializer.scala
@@ -6,7 +6,7 @@ package akka.stream
 import java.util.concurrent.TimeUnit
 import java.util.concurrent.atomic.AtomicBoolean
 
-import akka.actor.{ ActorContext, ActorRef, ActorRefFactory, ActorSystem, ExtendedActorSystem, Props }
+import akka.actor.{ ActorContext, ActorRef, ActorRefFactory, ActorSystem, ActorSystemImpl, ExtendedActorSystem, Props }
 import akka.event.LoggingAdapter
 import akka.util.Helpers.toRootLowerCase
 import akka.stream.impl._
@@ -60,11 +60,20 @@ object ActorMaterializer {
       system,
       materializerSettings,
       system.dispatchers,
-      context.actorOf(StreamSupervisor.props(materializerSettings, haveShutDown).withDispatcher(materializerSettings.dispatcher), StreamSupervisor.nextName()),
+      actorOfStreamSupervisor(materializerSettings, context, haveShutDown),
       haveShutDown,
       FlowNames(system).name.copy(namePrefix))
   }
 
+  private def actorOfStreamSupervisor(materializerSettings: ActorMaterializerSettings, context: ActorRefFactory, haveShutDown: AtomicBoolean) =
+    context match {
+      case s: ExtendedActorSystem ⇒
+        s.systemActorOf(StreamSupervisor.props(materializerSettings, haveShutDown).withDispatcher(materializerSettings.dispatcher), StreamSupervisor.nextName())
+
+      case a: ActorContext ⇒
+        a.actorOf(StreamSupervisor.props(materializerSettings, haveShutDown).withDispatcher(materializerSettings.dispatcher), StreamSupervisor.nextName())
+    }
+
   /**
    * Scala API: * Scala API: Creates an ActorMaterializer that can materialize stream blueprints as running streams.
    *
diff --git a/akka-testkit-typed/src/main/scala/akka/testkit/typed/TestKit.scala b/akka-testkit-typed/src/main/scala/akka/testkit/typed/TestKit.scala
index 28b4547ca8..a817d63a96 100644
--- a/akka-testkit-typed/src/main/scala/akka/testkit/typed/TestKit.scala
+++ b/akka-testkit-typed/src/main/scala/akka/testkit/typed/TestKit.scala
@@ -66,7 +66,7 @@ class TestKit(name: String, config: Option[Config]) extends TestKitBase {
   def this(name: String, config: Config) = this(name, Some(config))
 
   import TestKit._
-  implicit val system = ActorSystem(testKitGuardian, name, config = config)
+  implicit val system: ActorSystem[TestKitCommand] = ActorSystem(testKitGuardian, name, config = config)
 }
 
 @ApiMayChange