diff --git a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/QueueSourceSpec.scala b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/QueueSourceSpec.scala
index 55a0edd039..1a4b613160 100644
--- a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/QueueSourceSpec.scala
+++ b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/QueueSourceSpec.scala
@@ -194,6 +194,27 @@ class QueueSourceSpec extends AkkaSpec {
       queue.offer(1).onFailure { case e ⇒ e.isInstanceOf[IllegalStateException] should ===(true) }
     }
 
+    "not share future across materializations" in {
+      val source = Source.queue[String](1, OverflowStrategy.fail)
+
+      val mat1subscriber = TestSubscriber.probe[String]()
+      val mat2subscriber = TestSubscriber.probe[String]()
+      val sourceQueue1 = source.to(Sink.fromSubscriber(mat1subscriber)).run()
+      val sourceQueue2 = source.to(Sink.fromSubscriber(mat2subscriber)).run()
+
+      mat1subscriber.ensureSubscription()
+      mat2subscriber.ensureSubscription()
+
+      mat1subscriber.request(1)
+      sourceQueue1.offer("hello")
+      mat1subscriber.expectNext("hello")
+      mat1subscriber.cancel()
+      sourceQueue1.watchCompletion pipeTo testActor
+      expectMsg(Done)
+
+      sourceQueue2.watchCompletion().isCompleted should ===(false)
+    }
+
   }
 
 }
diff --git a/akka-stream/src/main/scala/akka/stream/impl/Sources.scala b/akka-stream/src/main/scala/akka/stream/impl/Sources.scala
index c11a41476d..f11b8c494c 100644
--- a/akka-stream/src/main/scala/akka/stream/impl/Sources.scala
+++ b/akka-stream/src/main/scala/akka/stream/impl/Sources.scala
@@ -20,9 +20,9 @@ final private[stream] class QueueSource[T](maxBuffer: Int, overflowStrategy: Ove
 
   val out = Outlet[T]("queueSource.out")
   override val shape: SourceShape[T] = SourceShape.of(out)
-  val completion = Promise[Done]
 
   override def createLogicAndMaterializedValue(inheritedAttributes: Attributes) = {
+    val completion = Promise[Done]
     val stageLogic = new GraphStageLogic(shape) with CallbackWrapper[(T, Offered)] {
       var buffer: Buffer[T] = _
       var pendingOffer: Option[(T, Offered)] = None
diff --git a/akka-stream/src/main/scala/akka/stream/impl/io/TcpStages.scala b/akka-stream/src/main/scala/akka/stream/impl/io/TcpStages.scala
index ca6538f59a..3ac29119a7 100644
--- a/akka-stream/src/main/scala/akka/stream/impl/io/TcpStages.scala
+++ b/akka-stream/src/main/scala/akka/stream/impl/io/TcpStages.scala
@@ -40,14 +40,14 @@ private[stream] class ConnectionSourceStage(val tcpManager: ActorRef,
   override def initialAttributes = Attributes.name("ConnectionSource")
   val shape: SourceShape[StreamTcp.IncomingConnection] = SourceShape(out)
 
-  private val connectionFlowsAwaitingInitialization = new AtomicLong()
-
   // TODO: Timeout on bind
   override def createLogicAndMaterializedValue(inheritedAttributes: Attributes): (GraphStageLogic, Future[ServerBinding]) = {
     val bindingPromise = Promise[ServerBinding]
 
     val logic = new TimerGraphStageLogic(shape) {
       implicit def self: ActorRef = stageActor.ref
+
+      val connectionFlowsAwaitingInitialization = new AtomicLong()
       var listener: ActorRef = _
       var unbindPromise = Promise[Unit]()
 
diff --git a/project/MiMa.scala b/project/MiMa.scala
index 4f4d9fd896..adba135c98 100644
--- a/project/MiMa.scala
+++ b/project/MiMa.scala
@@ -680,7 +680,10 @@ object MiMa extends AutoPlugin {
         ProblemFilters.exclude[FinalClassProblem]("akka.http.scaladsl.model.EntityStreamSizeException"),
 
         // #19849 content negotiation fixes
-        ProblemFilters.exclude[FinalClassProblem]("akka.http.scaladsl.marshalling.Marshal$UnacceptableResponseContentTypeException")
+        ProblemFilters.exclude[FinalClassProblem]("akka.http.scaladsl.marshalling.Marshal$UnacceptableResponseContentTypeException"),
+
+        // #20009 internal and shouldn't have been public
+        ProblemFilters.exclude[DirectMissingMethodProblem]("akka.stream.impl.QueueSource.completion")
       )
     )
   }