diff --git a/akka-stream/src/main/scala/akka/stream/javadsl/Flow.scala b/akka-stream/src/main/scala/akka/stream/javadsl/Flow.scala
index 9351d104e9..9b7fc45b00 100644
--- a/akka-stream/src/main/scala/akka/stream/javadsl/Flow.scala
+++ b/akka-stream/src/main/scala/akka/stream/javadsl/Flow.scala
@@ -103,7 +103,7 @@ class Flow[-In, +Out, +Mat](delegate: scaladsl.Flow[In, Out, Mat]) extends Graph
   /**
    * Join this [[Flow]] to another [[Flow]], by cross connecting the inputs and outputs, creating a [[RunnableGraph]]
    */
-  def joinMat[M, M2](flow: Graph[FlowShape[Out, In], M], combine: function.Function2[Mat, M, M2]): javadsl.RunnableFlow[M2] =
+  def joinMat[M, M2](flow: Graph[FlowShape[Out, In], M], combine: function.Function2[Mat, M, M2]): javadsl.RunnableGraph[M2] =
     new RunnableGraphAdapter(delegate.joinMat(flow)(combinerToScala(combine)))
 
   /**
diff --git a/akka-stream/src/main/scala/akka/stream/javadsl/Source.scala b/akka-stream/src/main/scala/akka/stream/javadsl/Source.scala
index f20132062b..68ea778c01 100644
--- a/akka-stream/src/main/scala/akka/stream/javadsl/Source.scala
+++ b/akka-stream/src/main/scala/akka/stream/javadsl/Source.scala
@@ -266,7 +266,7 @@ class Source[+Out, +Mat](delegate: scaladsl.Source[Out, Mat]) extends Graph[Sour
   /**
    * Connect this [[Source]] to a [[Sink]], concatenating the processing steps of both.
    */
-  def toMat[M, M2](sink: Graph[SinkShape[Out], M], combine: function.Function2[Mat, M, M2]): javadsl.RunnableFlow[M2] =
+  def toMat[M, M2](sink: Graph[SinkShape[Out], M], combine: function.Function2[Mat, M, M2]): javadsl.RunnableGraph[M2] =
     new RunnableGraphAdapter(delegate.toMat(sink)(combinerToScala(combine)))
 
   /**