diff --git a/akka-cluster/src/main/scala/akka/cluster/Cluster.scala b/akka-cluster/src/main/scala/akka/cluster/Cluster.scala
index 78bd91c8e1..a26befb875 100644
--- a/akka-cluster/src/main/scala/akka/cluster/Cluster.scala
+++ b/akka-cluster/src/main/scala/akka/cluster/Cluster.scala
@@ -500,7 +500,7 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
   /**
    * Shuts down all connections to other members, the cluster daemon and the periodic gossip and cleanup tasks.
    */
-  def shutdown() {
+  def shutdown(): Unit = {
     if (isRunning.compareAndSet(true, false)) {
       log.info("Cluster Node [{}] - Shutting down cluster Node and cluster daemons...", remoteAddress)
       gossipCanceller.cancel()
@@ -519,7 +519,7 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
    * Registers a listener to subscribe to cluster membership changes.
    */
   @tailrec
-  final def registerListener(listener: MembershipChangeListener) {
+  final def registerListener(listener: MembershipChangeListener): Unit = {
     val localState = state.get
     val newListeners = localState.memberMembershipChangeListeners + listener
     val newState = localState copy (memberMembershipChangeListeners = newListeners)
@@ -530,7 +530,7 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
    * Unsubscribes to cluster membership changes.
    */
   @tailrec
-  final def unregisterListener(listener: MembershipChangeListener) {
+  final def unregisterListener(listener: MembershipChangeListener): Unit = {
     val localState = state.get
     val newListeners = localState.memberMembershipChangeListeners - listener
     val newState = localState copy (memberMembershipChangeListeners = newListeners)
@@ -541,7 +541,7 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
    * Try to join this cluster node with the node specified by 'address'.
    * A 'Join(thisNodeAddress)' command is sent to the node to join.
    */
-  def join(address: Address) {
+  def join(address: Address): Unit = {
     val connection = clusterCommandConnectionFor(address)
     val command = ClusterAction.Join(remoteAddress)
     log.info("Cluster Node [{}] - Trying to send JOIN to [{}] through connection [{}]", remoteAddress, address, connection)
@@ -551,21 +551,21 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
   /**
    * Send command to issue state transition to LEAVING for the node specified by 'address'.
    */
-  def leave(address: Address) {
+  def leave(address: Address): Unit = {
     clusterCommandDaemon ! ClusterAction.Leave(address)
   }
 
   /**
    * Send command to issue state transition to from DOWN to EXITING for the node specified by 'address'.
    */
-  def down(address: Address) {
+  def down(address: Address): Unit = {
     clusterCommandDaemon ! ClusterAction.Down(address)
   }
 
   /**
    * Send command to issue state transition to REMOVED for the node specified by 'address'.
    */
-  def remove(address: Address) {
+  def remove(address: Address): Unit = {
     clusterCommandDaemon ! ClusterAction.Remove(address)
   }
 
@@ -578,7 +578,7 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
    * New node joining.
    */
   @tailrec
-  private[cluster] final def joining(node: Address) {
+  private[cluster] final def joining(node: Address): Unit = {
     log.info("Cluster Node [{}] - Node [{}] is JOINING", remoteAddress, node)
 
     val localState = state.get
@@ -611,28 +611,28 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
   /**
    * State transition to UP.
    */
-  private[cluster] final def up(address: Address) {
+  private[cluster] final def up(address: Address): Unit = {
     log.info("Cluster Node [{}] - Marking node [{}] as UP", remoteAddress, address)
   }
 
   /**
    * State transition to LEAVING.
    */
-  private[cluster] final def leaving(address: Address) {
+  private[cluster] final def leaving(address: Address): Unit = {
     log.info("Cluster Node [{}] - Marking node [{}] as LEAVING", remoteAddress, address)
   }
 
   /**
    * State transition to EXITING.
    */
-  private[cluster] final def exiting(address: Address) {
+  private[cluster] final def exiting(address: Address): Unit = {
     log.info("Cluster Node [{}] - Marking node [{}] as EXITING", remoteAddress, address)
   }
 
   /**
    * State transition to REMOVED.
    */
-  private[cluster] final def removing(address: Address) {
+  private[cluster] final def removing(address: Address): Unit = {
     log.info("Cluster Node [{}] - Marking node [{}] as REMOVED", remoteAddress, address)
   }
 
@@ -644,7 +644,7 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
    * to this node and it will then go through the normal JOINING procedure.
    */
   @tailrec
-  final private[cluster] def downing(address: Address) {
+  final private[cluster] def downing(address: Address): Unit = {
     val localState = state.get
     val localGossip = localState.latestGossip
     val localMembers = localGossip.members
@@ -705,7 +705,7 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
    * Receive new gossip.
    */
   @tailrec
-  final private[cluster] def receive(sender: Member, remoteGossip: Gossip) {
+  final private[cluster] def receive(sender: Member, remoteGossip: Gossip): Unit = {
     val localState = state.get
     val localGossip = localState.latestGossip
 
@@ -746,14 +746,9 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
   }
 
   /**
-   * Joins the pre-configured contact point and retrieves current gossip state.
+   * Joins the pre-configured contact point.
    */
-  private def autoJoin() = nodeToJoin foreach { address ⇒
-    val connection = clusterCommandConnectionFor(address)
-    val command = ClusterAction.Join(remoteAddress)
-    log.info("Cluster Node [{}] - Sending [{}] to [{}] through connection [{}]", remoteAddress, command, address, connection)
-    connection ! command
-  }
+  private def autoJoin(): Unit = nodeToJoin foreach join
 
   /**
    * Switches the member status.
@@ -793,7 +788,7 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
   /**
    * Gossips latest gossip to an address.
    */
-  private def gossipTo(address: Address) {
+  private def gossipTo(address: Address): Unit = {
     val connection = clusterGossipConnectionFor(address)
     log.debug("Cluster Node [{}] - Gossiping to [{}]", remoteAddress, connection)
     connection ! GossipEnvelope(self, latestGossip)
@@ -818,10 +813,8 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
   /**
    * Initates a new round of gossip.
    */
-  private def gossip() {
+  private def gossip(): Unit = {
     val localState = state.get
-    val localGossip = localState.latestGossip
-    val localMembers = localGossip.members
 
     if (!isSingletonCluster(localState) && isAvailable(localState)) {
       // only gossip if we are a non-singleton cluster and available
@@ -860,7 +853,7 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
    * Reaps the unreachable members (moves them to the 'unreachable' list in the cluster overview) according to the failure detector's verdict.
    */
   @tailrec
-  final private def reapUnreachableMembers() {
+  final private def reapUnreachableMembers(): Unit = {
     val localState = state.get
 
     if (!isSingletonCluster(localState) && isAvailable(localState)) {
@@ -905,7 +898,7 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
    * Runs periodic leader actions, such as auto-downing unreachable nodes, assigning partitions etc.
    */
   @tailrec
-  final private def leaderActions() {
+  final private def leaderActions(): Unit = {
     val localState = state.get
     val localGossip = localState.latestGossip
     val localMembers = localGossip.members
@@ -917,7 +910,7 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
 
       val localOverview = localGossip.overview
       val localSeen = localOverview.seen
-      val localUnreachableMembers = localGossip.overview.unreachable
+      val localUnreachableMembers = localOverview.unreachable
 
       // Leader actions are as follows:
       //   1. Move JOINING     => UP
@@ -986,7 +979,7 @@ class Cluster(system: ExtendedActorSystem) extends Extension { clusterNode ⇒
         if (!state.compareAndSet(localState, newState)) leaderActions() // recur
         else {
           if (convergence(newState.latestGossip).isDefined) {
-            newState.memberMembershipChangeListeners map { _ notify newGossip.members }
+            newState.memberMembershipChangeListeners foreach { _ notify newGossip.members }
           }
         }
       }