diff --git a/akka-cluster/src/main/scala/akka/cluster/Cluster.scala b/akka-cluster/src/main/scala/akka/cluster/Cluster.scala
index c090995e4c..5bc968920a 100644
--- a/akka-cluster/src/main/scala/akka/cluster/Cluster.scala
+++ b/akka-cluster/src/main/scala/akka/cluster/Cluster.scala
@@ -195,9 +195,9 @@ case class Gossip(
   /**
    * Increments the version for this 'Node'.
    */
-  def +(node: VectorClock.Node): Gossip = copy(version = version + node)
+  def :+(node: VectorClock.Node): Gossip = copy(version = version :+ node)
 
-  def +(member: Member): Gossip = {
+  def :+(member: Member): Gossip = {
     if (members contains member) this
     else this copy (members = members + member)
   }
@@ -424,7 +424,7 @@ class Cluster(system: ExtendedActorSystem, val failureDetector: FailureDetector)
 
   private val state = {
     val member = Member(selfAddress, MemberStatus.Joining)
-    val versionedGossip = Gossip(members = Gossip.emptyMembers + member) + vclockNode // add me as member and update my vector clock
+    val versionedGossip = Gossip(members = Gossip.emptyMembers + member) :+ vclockNode // add me as member and update my vector clock
     val seenVersionedGossip = versionedGossip seen selfAddress
     new AtomicReference[State](State(seenVersionedGossip))
   }
@@ -658,7 +658,7 @@ class Cluster(system: ExtendedActorSystem, val failureDetector: FailureDetector)
       val newMembers = localMembers + Member(node, MemberStatus.Joining) // add joining node as Joining
       val newGossip = localGossip copy (overview = newOverview, members = newMembers)
 
-      val versionedGossip = newGossip + vclockNode
+      val versionedGossip = newGossip :+ vclockNode
       val seenVersionedGossip = versionedGossip seen selfAddress
 
       val newState = localState copy (latestGossip = seenVersionedGossip)
@@ -686,7 +686,7 @@ class Cluster(system: ExtendedActorSystem, val failureDetector: FailureDetector)
     val newMembers = localMembers + Member(address, MemberStatus.Leaving) // mark node as LEAVING
     val newGossip = localGossip copy (members = newMembers)
 
-    val versionedGossip = newGossip + vclockNode
+    val versionedGossip = newGossip :+ vclockNode
     val seenVersionedGossip = versionedGossip seen selfAddress
 
     val newState = localState copy (latestGossip = seenVersionedGossip)
@@ -772,7 +772,7 @@ class Cluster(system: ExtendedActorSystem, val failureDetector: FailureDetector)
 
     val newOverview = localOverview copy (seen = newSeen, unreachable = newUnreachablePlusNewlyDownedMembers) // update gossip overview
     val newGossip = localGossip copy (overview = newOverview, members = newMembers) // update gossip
-    val versionedGossip = newGossip + vclockNode
+    val versionedGossip = newGossip :+ vclockNode
     val newState = localState copy (latestGossip = versionedGossip seen selfAddress)
 
     if (!state.compareAndSet(localState, newState)) downing(address) // recur if we fail the update
@@ -793,7 +793,7 @@ class Cluster(system: ExtendedActorSystem, val failureDetector: FailureDetector)
       if (remoteGossip.version <> localGossip.version) {
         // concurrent
         val mergedGossip = remoteGossip merge localGossip
-        val versionedMergedGossip = mergedGossip + vclockNode
+        val versionedMergedGossip = mergedGossip :+ vclockNode
 
         // FIXME change to debug log level, when failure detector is stable
         log.info(
@@ -855,7 +855,7 @@ class Cluster(system: ExtendedActorSystem, val failureDetector: FailureDetector)
     val newGossip = localGossip copy (members = newMembers)
 
     // version my changes
-    val versionedGossip = newGossip + vclockNode
+    val versionedGossip = newGossip :+ vclockNode
     val seenVersionedGossip = versionedGossip seen selfAddress
 
     state copy (latestGossip = seenVersionedGossip)
@@ -992,7 +992,7 @@ class Cluster(system: ExtendedActorSystem, val failureDetector: FailureDetector)
         val newGossip = localGossip copy (overview = newOverview, members = newMembers)
 
         // updating vclock and 'seen' table
-        val versionedGossip = newGossip + vclockNode
+        val versionedGossip = newGossip :+ vclockNode
         val seenVersionedGossip = versionedGossip seen selfAddress
 
         val newState = localState copy (latestGossip = seenVersionedGossip)
@@ -1111,7 +1111,7 @@ class Cluster(system: ExtendedActorSystem, val failureDetector: FailureDetector)
         // ----------------------
         // 5. Updating the vclock version for the changes
         // ----------------------
-        val versionedGossip = newGossip + vclockNode
+        val versionedGossip = newGossip :+ vclockNode
 
         // ----------------------
         // 6. Updating the 'seen' table
diff --git a/akka-cluster/src/main/scala/akka/cluster/VectorClock.scala b/akka-cluster/src/main/scala/akka/cluster/VectorClock.scala
index 82c1b9881d..ed6724058f 100644
--- a/akka-cluster/src/main/scala/akka/cluster/VectorClock.scala
+++ b/akka-cluster/src/main/scala/akka/cluster/VectorClock.scala
@@ -19,7 +19,7 @@ class VectorClockException(message: String) extends AkkaException(message)
  */
 trait Versioned[T] {
   def version: VectorClock
-  def +(node: VectorClock.Node): T
+  def :+(node: VectorClock.Node): T
 }
 
 /**
@@ -142,7 +142,7 @@ case class VectorClock(
   /**
    * Increment the version for the node passed as argument. Returns a new VectorClock.
    */
-  def +(node: Node): VectorClock = copy(versions = versions + (node -> Timestamp()))
+  def :+(node: Node): VectorClock = copy(versions = versions + (node -> Timestamp()))
 
   /**
    * Returns true if <code>this</code> and <code>that</code> are concurrent else false.
diff --git a/akka-cluster/src/test/scala/akka/cluster/VectorClockSpec.scala b/akka-cluster/src/test/scala/akka/cluster/VectorClockSpec.scala
index de1142b668..19ad9410c4 100644
--- a/akka-cluster/src/test/scala/akka/cluster/VectorClockSpec.scala
+++ b/akka-cluster/src/test/scala/akka/cluster/VectorClockSpec.scala
@@ -27,67 +27,67 @@ class VectorClockSpec extends AkkaSpec {
 
     "pass misc comparison test 1" in {
       val clock1_1 = VectorClock()
-      val clock2_1 = clock1_1 + Node("1")
-      val clock3_1 = clock2_1 + Node("2")
-      val clock4_1 = clock3_1 + Node("1")
+      val clock2_1 = clock1_1 :+ Node("1")
+      val clock3_1 = clock2_1 :+ Node("2")
+      val clock4_1 = clock3_1 :+ Node("1")
 
       val clock1_2 = VectorClock()
-      val clock2_2 = clock1_2 + Node("1")
-      val clock3_2 = clock2_2 + Node("2")
-      val clock4_2 = clock3_2 + Node("1")
+      val clock2_2 = clock1_2 :+ Node("1")
+      val clock3_2 = clock2_2 :+ Node("2")
+      val clock4_2 = clock3_2 :+ Node("1")
 
       clock4_1 <> clock4_2 must be(false)
     }
 
     "pass misc comparison test 2" in {
       val clock1_1 = VectorClock()
-      val clock2_1 = clock1_1 + Node("1")
-      val clock3_1 = clock2_1 + Node("2")
-      val clock4_1 = clock3_1 + Node("1")
+      val clock2_1 = clock1_1 :+ Node("1")
+      val clock3_1 = clock2_1 :+ Node("2")
+      val clock4_1 = clock3_1 :+ Node("1")
 
       val clock1_2 = VectorClock()
-      val clock2_2 = clock1_2 + Node("1")
-      val clock3_2 = clock2_2 + Node("2")
-      val clock4_2 = clock3_2 + Node("1")
-      val clock5_2 = clock4_2 + Node("3")
+      val clock2_2 = clock1_2 :+ Node("1")
+      val clock3_2 = clock2_2 :+ Node("2")
+      val clock4_2 = clock3_2 :+ Node("1")
+      val clock5_2 = clock4_2 :+ Node("3")
 
       clock4_1 < clock5_2 must be(true)
     }
 
     "pass misc comparison test 3" in {
       var clock1_1 = VectorClock()
-      val clock2_1 = clock1_1 + Node("1")
+      val clock2_1 = clock1_1 :+ Node("1")
 
       val clock1_2 = VectorClock()
-      val clock2_2 = clock1_2 + Node("2")
+      val clock2_2 = clock1_2 :+ Node("2")
 
       clock2_1 <> clock2_2 must be(true)
     }
 
     "pass misc comparison test 4" in {
       val clock1_3 = VectorClock()
-      val clock2_3 = clock1_3 + Node("1")
-      val clock3_3 = clock2_3 + Node("2")
-      val clock4_3 = clock3_3 + Node("1")
+      val clock2_3 = clock1_3 :+ Node("1")
+      val clock3_3 = clock2_3 :+ Node("2")
+      val clock4_3 = clock3_3 :+ Node("1")
 
       val clock1_4 = VectorClock()
-      val clock2_4 = clock1_4 + Node("1")
-      val clock3_4 = clock2_4 + Node("1")
-      val clock4_4 = clock3_4 + Node("3")
+      val clock2_4 = clock1_4 :+ Node("1")
+      val clock3_4 = clock2_4 :+ Node("1")
+      val clock4_4 = clock3_4 :+ Node("3")
 
       clock4_3 <> clock4_4 must be(true)
     }
 
     "pass misc comparison test 5" in {
       val clock1_1 = VectorClock()
-      val clock2_1 = clock1_1 + Node("2")
-      val clock3_1 = clock2_1 + Node("2")
+      val clock2_1 = clock1_1 :+ Node("2")
+      val clock3_1 = clock2_1 :+ Node("2")
 
       val clock1_2 = VectorClock()
-      val clock2_2 = clock1_2 + Node("1")
-      val clock3_2 = clock2_2 + Node("2")
-      val clock4_2 = clock3_2 + Node("2")
-      val clock5_2 = clock4_2 + Node("3")
+      val clock2_2 = clock1_2 :+ Node("1")
+      val clock3_2 = clock2_2 :+ Node("2")
+      val clock4_2 = clock3_2 :+ Node("2")
+      val clock5_2 = clock4_2 :+ Node("3")
 
       clock3_1 < clock5_2 must be(true)
       clock5_2 > clock3_1 must be(true)
@@ -95,12 +95,12 @@ class VectorClockSpec extends AkkaSpec {
 
     "pass misc comparison test 6" in {
       val clock1_1 = VectorClock()
-      val clock2_1 = clock1_1 + Node("1")
-      val clock3_1 = clock2_1 + Node("2")
+      val clock2_1 = clock1_1 :+ Node("1")
+      val clock3_1 = clock2_1 :+ Node("2")
 
       val clock1_2 = VectorClock()
-      val clock2_2 = clock1_2 + Node("1")
-      val clock3_2 = clock2_2 + Node("1")
+      val clock2_2 = clock1_2 :+ Node("1")
+      val clock3_2 = clock2_2 :+ Node("1")
 
       clock3_1 <> clock3_2 must be(true)
       clock3_2 <> clock3_1 must be(true)
@@ -108,14 +108,14 @@ class VectorClockSpec extends AkkaSpec {
 
     "pass misc comparison test 7" in {
       val clock1_1 = VectorClock()
-      val clock2_1 = clock1_1 + Node("1")
-      val clock3_1 = clock2_1 + Node("2")
-      val clock4_1 = clock3_1 + Node("2")
-      val clock5_1 = clock4_1 + Node("3")
+      val clock2_1 = clock1_1 :+ Node("1")
+      val clock3_1 = clock2_1 :+ Node("2")
+      val clock4_1 = clock3_1 :+ Node("2")
+      val clock5_1 = clock4_1 :+ Node("3")
 
       val clock1_2 = VectorClock()
-      val clock2_2 = clock1_2 + Node("2")
-      val clock3_2 = clock2_2 + Node("2")
+      val clock2_2 = clock1_2 :+ Node("2")
+      val clock3_2 = clock2_2 :+ Node("2")
 
       clock5_1 <> clock3_2 must be(true)
       clock3_2 <> clock5_1 must be(true)
@@ -127,14 +127,14 @@ class VectorClockSpec extends AkkaSpec {
       val node3 = Node("3")
 
       val clock1_1 = VectorClock()
-      val clock2_1 = clock1_1 + node1
-      val clock3_1 = clock2_1 + node2
-      val clock4_1 = clock3_1 + node2
-      val clock5_1 = clock4_1 + node3
+      val clock2_1 = clock1_1 :+ node1
+      val clock3_1 = clock2_1 :+ node2
+      val clock4_1 = clock3_1 :+ node2
+      val clock5_1 = clock4_1 :+ node3
 
       val clock1_2 = VectorClock()
-      val clock2_2 = clock1_2 + node2
-      val clock3_2 = clock2_2 + node2
+      val clock2_2 = clock1_2 :+ node2
+      val clock3_2 = clock2_2 :+ node2
 
       val merged1 = clock3_2 merge clock5_1
       merged1.versions.size must be(3)
@@ -164,14 +164,14 @@ class VectorClockSpec extends AkkaSpec {
       val node4 = Node("4")
 
       val clock1_1 = VectorClock()
-      val clock2_1 = clock1_1 + node1
-      val clock3_1 = clock2_1 + node2
-      val clock4_1 = clock3_1 + node2
-      val clock5_1 = clock4_1 + node3
+      val clock2_1 = clock1_1 :+ node1
+      val clock3_1 = clock2_1 :+ node2
+      val clock4_1 = clock3_1 :+ node2
+      val clock5_1 = clock4_1 :+ node3
 
       val clock1_2 = VectorClock()
-      val clock2_2 = clock1_2 + node4
-      val clock3_2 = clock2_2 + node4
+      val clock2_2 = clock1_2 :+ node4
+      val clock3_2 = clock2_2 :+ node4
 
       val merged1 = clock3_2 merge clock5_1
       merged1.versions.size must be(4)
@@ -204,8 +204,8 @@ class VectorClockSpec extends AkkaSpec {
       val v1 = VectorClock()
       val v2 = VectorClock()
 
-      val vv1 = v1 + node1
-      val vv2 = v2 + node2
+      val vv1 = v1 :+ node1
+      val vv2 = v2 :+ node2
 
       (vv1 > v1) must equal(true)
       (vv2 > v2) must equal(true)
@@ -225,12 +225,12 @@ class VectorClockSpec extends AkkaSpec {
       val a = VectorClock()
       val b = VectorClock()
 
-      val a1 = a + node1
-      val b1 = b + node2
+      val a1 = a :+ node1
+      val b1 = b :+ node2
 
-      var a2 = a1 + node1
+      var a2 = a1 :+ node1
       var c = a2.merge(b1)
-      var c1 = c + node3
+      var c1 = c :+ node3
 
       (c1 > a2) must equal(true)
       (c1 > b1) must equal(true)
@@ -239,7 +239,7 @@ class VectorClockSpec extends AkkaSpec {
 
   "An instance of Versioned" must {
     class TestVersioned(val version: VectorClock = VectorClock()) extends Versioned[TestVersioned] {
-      def +(node: Node): TestVersioned = new TestVersioned(version + node)
+      def :+(node: Node): TestVersioned = new TestVersioned(version :+ node)
     }
 
     import Versioned.latestVersionOf
@@ -251,67 +251,67 @@ class VectorClockSpec extends AkkaSpec {
 
     "happen before an identical versioned with a single additional event" in {
       val versioned1_1 = new TestVersioned()
-      val versioned2_1 = versioned1_1 + Node("1")
-      val versioned3_1 = versioned2_1 + Node("2")
-      val versioned4_1 = versioned3_1 + Node("1")
+      val versioned2_1 = versioned1_1 :+ Node("1")
+      val versioned3_1 = versioned2_1 :+ Node("2")
+      val versioned4_1 = versioned3_1 :+ Node("1")
 
       val versioned1_2 = new TestVersioned()
-      val versioned2_2 = versioned1_2 + Node("1")
-      val versioned3_2 = versioned2_2 + Node("2")
-      val versioned4_2 = versioned3_2 + Node("1")
-      val versioned5_2 = versioned4_2 + Node("3")
+      val versioned2_2 = versioned1_2 :+ Node("1")
+      val versioned3_2 = versioned2_2 :+ Node("2")
+      val versioned4_2 = versioned3_2 :+ Node("1")
+      val versioned5_2 = versioned4_2 :+ Node("3")
 
       latestVersionOf[TestVersioned](versioned4_1, versioned5_2) must be(versioned5_2)
     }
 
     "pass misc comparison test 1" in {
       var versioned1_1 = new TestVersioned()
-      val versioned2_1 = versioned1_1 + Node("1")
+      val versioned2_1 = versioned1_1 :+ Node("1")
 
       val versioned1_2 = new TestVersioned()
-      val versioned2_2 = versioned1_2 + Node("2")
+      val versioned2_2 = versioned1_2 :+ Node("2")
 
       latestVersionOf[TestVersioned](versioned2_1, versioned2_2) must be(versioned2_2)
     }
 
     "pass misc comparison test 2" in {
       val versioned1_3 = new TestVersioned()
-      val versioned2_3 = versioned1_3 + Node("1")
-      val versioned3_3 = versioned2_3 + Node("2")
-      val versioned4_3 = versioned3_3 + Node("1")
+      val versioned2_3 = versioned1_3 :+ Node("1")
+      val versioned3_3 = versioned2_3 :+ Node("2")
+      val versioned4_3 = versioned3_3 :+ Node("1")
 
       val versioned1_4 = new TestVersioned()
-      val versioned2_4 = versioned1_4 + Node("1")
-      val versioned3_4 = versioned2_4 + Node("1")
-      val versioned4_4 = versioned3_4 + Node("3")
+      val versioned2_4 = versioned1_4 :+ Node("1")
+      val versioned3_4 = versioned2_4 :+ Node("1")
+      val versioned4_4 = versioned3_4 :+ Node("3")
 
       latestVersionOf[TestVersioned](versioned4_3, versioned4_4) must be(versioned4_4)
     }
 
     "pass misc comparison test 3" in {
       val versioned1_1 = new TestVersioned()
-      val versioned2_1 = versioned1_1 + Node("2")
-      val versioned3_1 = versioned2_1 + Node("2")
+      val versioned2_1 = versioned1_1 :+ Node("2")
+      val versioned3_1 = versioned2_1 :+ Node("2")
 
       val versioned1_2 = new TestVersioned()
-      val versioned2_2 = versioned1_2 + Node("1")
-      val versioned3_2 = versioned2_2 + Node("2")
-      val versioned4_2 = versioned3_2 + Node("2")
-      val versioned5_2 = versioned4_2 + Node("3")
+      val versioned2_2 = versioned1_2 :+ Node("1")
+      val versioned3_2 = versioned2_2 :+ Node("2")
+      val versioned4_2 = versioned3_2 :+ Node("2")
+      val versioned5_2 = versioned4_2 :+ Node("3")
 
       latestVersionOf[TestVersioned](versioned3_1, versioned5_2) must be(versioned5_2)
     }
 
     "pass misc comparison test 4" in {
       val versioned1_1 = new TestVersioned()
-      val versioned2_1 = versioned1_1 + Node("1")
-      val versioned3_1 = versioned2_1 + Node("2")
-      val versioned4_1 = versioned3_1 + Node("2")
-      val versioned5_1 = versioned4_1 + Node("3")
+      val versioned2_1 = versioned1_1 :+ Node("1")
+      val versioned3_1 = versioned2_1 :+ Node("2")
+      val versioned4_1 = versioned3_1 :+ Node("2")
+      val versioned5_1 = versioned4_1 :+ Node("3")
 
       val versioned1_2 = new TestVersioned()
-      val versioned2_2 = versioned1_2 + Node("2")
-      val versioned3_2 = versioned2_2 + Node("2")
+      val versioned2_2 = versioned1_2 :+ Node("2")
+      val versioned3_2 = versioned2_2 :+ Node("2")
 
       latestVersionOf[TestVersioned](versioned5_1, versioned3_2) must be(versioned3_2)
     }