diff --git a/akka-multi-node-testkit/src/main/mima-filters/2.6.4.backwards.excludes/RemoteConnection-shutdown.excludes b/akka-multi-node-testkit/src/main/mima-filters/2.6.4.backwards.excludes/RemoteConnection-shutdown.excludes
new file mode 100644
index 0000000000..f3000e0786
--- /dev/null
+++ b/akka-multi-node-testkit/src/main/mima-filters/2.6.4.backwards.excludes/RemoteConnection-shutdown.excludes
@@ -0,0 +1 @@
+ProblemFilters.exclude[IncompatibleResultTypeProblem]("akka.remote.testconductor.RemoteConnection.shutdown")
diff --git a/akka-multi-node-testkit/src/main/scala/akka/remote/testconductor/RemoteConnection.scala b/akka-multi-node-testkit/src/main/scala/akka/remote/testconductor/RemoteConnection.scala
index 3e8f37cb7b..75aeb66322 100644
--- a/akka-multi-node-testkit/src/main/scala/akka/remote/testconductor/RemoteConnection.scala
+++ b/akka-multi-node-testkit/src/main/scala/akka/remote/testconductor/RemoteConnection.scala
@@ -112,7 +112,7 @@ private[akka] object RemoteConnection {
     case _                    => "[unknown]"
   }
 
-  def shutdown(channel: Channel) = {
+  def shutdown(channel: Channel): Unit = {
     try {
       try channel.close()
       finally try channel.getFactory.shutdown()