diff --git a/akka-docs-dev/rst/scala/code/docs/stream/CompositionDocSpec.scala b/akka-docs-dev/rst/scala/code/docs/stream/CompositionDocSpec.scala
index 61ae6fedeb..3f58420996 100644
--- a/akka-docs-dev/rst/scala/code/docs/stream/CompositionDocSpec.scala
+++ b/akka-docs-dev/rst/scala/code/docs/stream/CompositionDocSpec.scala
@@ -78,13 +78,13 @@ class CompositionDocSpec extends AkkaSpec {
     //#complex-graph
     import FlowGraph.Implicits._
     RunnableGraph.fromGraph(FlowGraph.create() { implicit builder =>
-      val A: Outlet[Int]                  = builder.add(Source.single(0))
+      val A: Outlet[Int]                  = builder.add(Source.single(0)).outlet
       val B: UniformFanOutShape[Int, Int] = builder.add(Broadcast[Int](2))
       val C: UniformFanInShape[Int, Int]  = builder.add(Merge[Int](2))
       val D: FlowShape[Int, Int]          = builder.add(Flow[Int].map(_ + 1))
       val E: UniformFanOutShape[Int, Int] = builder.add(Balance[Int](2))
       val F: UniformFanInShape[Int, Int]  = builder.add(Merge[Int](2))
-      val G: Inlet[Any]                   = builder.add(Sink.foreach(println))
+      val G: Inlet[Any]                   = builder.add(Sink.foreach(println)).inlet
 
                     C     <~      F
       A  ~>  B  ~>  C     ~>      F
diff --git a/akka-http-core/src/test/scala/akka/http/impl/engine/ws/MessageSpec.scala b/akka-http-core/src/test/scala/akka/http/impl/engine/ws/MessageSpec.scala
index 468465bfd1..49b4024b93 100644
--- a/akka-http-core/src/test/scala/akka/http/impl/engine/ws/MessageSpec.scala
+++ b/akka-http-core/src/test/scala/akka/http/impl/engine/ws/MessageSpec.scala
@@ -819,8 +819,8 @@ class MessageSpec extends FreeSpec with Matchers with WithMaterializerSpec {
     val messageHandler: Flow[Message, Message, Unit] =
       Flow.fromGraph {
         FlowGraph.create() { implicit b ⇒
-          val in = b.add(Sink(messageIn))
-          val out = b.add(Source(messageOut))
+          val in = b.add(Sink(messageIn)).inlet
+          val out = b.add(Source(messageOut)).outlet
 
           FlowShape[Message, Message](in, out)
         }
diff --git a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/BidiFlowSpec.scala b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/BidiFlowSpec.scala
index b41196843d..302d9d1b86 100644
--- a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/BidiFlowSpec.scala
+++ b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/BidiFlowSpec.scala
@@ -103,7 +103,7 @@ class BidiFlowSpec extends AkkaSpec with ConversionCheckedTripleEquals {
         sink ⇒
           val flow = b.add(Flow[Long].grouped(10))
           flow ~> sink
-          FlowShape(flow.inlet, b.add(Source.single(ByteString("10"))))
+          FlowShape(flow.inlet, b.add(Source.single(ByteString("10"))).outlet)
       })
       val ((l, m), r) = left.joinMat(bidiMat)(Keep.both).joinMat(right)(Keep.both).run()
       Await.result(l, 1.second) should ===(1)
diff --git a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/ReverseArrowSpec.scala b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/ReverseArrowSpec.scala
index 276236701f..75da9d9253 100644
--- a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/ReverseArrowSpec.scala
+++ b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/ReverseArrowSpec.scala
@@ -44,7 +44,7 @@ class ReverseArrowSpec extends AkkaSpec with ConversionCheckedTripleEquals {
 
     "not work from Outlets" in {
       RunnableGraph.fromGraph(FlowGraph.create() { implicit b ⇒
-        val o: Outlet[Int] = b.add(source)
+        val o: Outlet[Int] = b.add(source).outlet
         "o <~ source" shouldNot compile
         sink <~ o
         ClosedShape
@@ -97,7 +97,7 @@ class ReverseArrowSpec extends AkkaSpec with ConversionCheckedTripleEquals {
     "work towards Outlets" in {
       Await.result(RunnableGraph.fromGraph(FlowGraph.create(sink) { implicit b ⇒
         s ⇒
-          val o: Outlet[Int] = b.add(source)
+          val o: Outlet[Int] = b.add(source).outlet
           s <~ o
           ClosedShape
       }).run(), 1.second) should ===(Seq(1, 2, 3))
diff --git a/akka-stream/src/main/scala/akka/stream/scaladsl/Graph.scala b/akka-stream/src/main/scala/akka/stream/scaladsl/Graph.scala
index 21459c2347..2f557e88d4 100644
--- a/akka-stream/src/main/scala/akka/stream/scaladsl/Graph.scala
+++ b/akka-stream/src/main/scala/akka/stream/scaladsl/Graph.scala
@@ -570,15 +570,9 @@ object FlowGraph extends GraphApply {
   class Builder[+M] private[stream] () {
     private var moduleInProgress: Module = EmptyModule
 
-    private[FlowGraph] def addEdge[A1, A >: A1, B, B1 >: B, M2](from: Outlet[A1], via: Graph[FlowShape[A, B], M2], to: Inlet[B1]): Unit = {
-      val flowCopy = via.module.carbonCopy
-      moduleInProgress =
-        moduleInProgress
-          .compose(flowCopy)
-          .wire(from, flowCopy.shape.inlets.head)
-          .wire(flowCopy.shape.outlets.head, to)
-    }
-
+    /**
+     * INTERNAL API
+     */
     private[FlowGraph] def addEdge[T, U >: T](from: Outlet[T], to: Inlet[U]): Unit =
       moduleInProgress = moduleInProgress.wire(from, to)
 
@@ -620,9 +614,6 @@ object FlowGraph extends GraphApply {
       graph.shape.copyFromPorts(copy.shape.inlets, copy.shape.outlets).asInstanceOf[S]
     }
 
-    def add[T](s: Source[T, _]): Outlet[T] = add(s: Graph[SourceShape[T], _]).outlet
-    def add[T](s: Sink[T, _]): Inlet[T] = add(s: Graph[SinkShape[T], _]).inlet
-
     /**
      * Returns an [[Outlet]] that gives access to the materialized value of this graph. Once the graph is materialized
      * this outlet will emit exactly one element which is the materialized value. It is possible to expose this